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<button class="button is-small is-link">Go</button> </div> </div> </form> </div> </div> <nav class="pagination is-small is-centered breathe-horizontal" role="navigation" aria-label="pagination"> <a href="" class="pagination-previous is-invisible">Previous </a> <a href="/search/?searchtype=author&query=Case%2C+A+W&start=50" class="pagination-next" >Next </a> <ul class="pagination-list"> <li> <a href="/search/?searchtype=author&query=Case%2C+A+W&start=0" class="pagination-link is-current" aria-label="Goto page 1">1 </a> </li> <li> <a href="/search/?searchtype=author&query=Case%2C+A+W&start=50" class="pagination-link " aria-label="Page 2" aria-current="page">2 </a> </li> </ul> </nav> <ol class="breathe-horizontal" start="1"> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2310.12134">arXiv:2310.12134</a> <span> [<a href="https://arxiv.org/pdf/2310.12134">pdf</a>, <a href="https://arxiv.org/format/2310.12134">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Solar and Stellar Astrophysics">astro-ph.SR</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Earth and Planetary Astrophysics">astro-ph.EP</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Plasma Physics">physics.plasm-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Space Physics">physics.space-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.3847/1538-4357/acf99a">10.3847/1538-4357/acf99a <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Are Switchback boundaries observed by Parker Solar Probe closed? </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Bizien%2C+N">Nina Bizien</a>, <a href="/search/physics?searchtype=author&query=de+Wit%2C+T+D">Thierry Dudok de Wit</a>, <a href="/search/physics?searchtype=author&query=Froment%2C+C">Clara Froment</a>, <a href="/search/physics?searchtype=author&query=Velli%2C+M">Marco Velli</a>, <a href="/search/physics?searchtype=author&query=Case%2C+A+W">Anthony W. Case</a>, <a href="/search/physics?searchtype=author&query=Bale%2C+S+D">Stuart D. Bale</a>, <a href="/search/physics?searchtype=author&query=Kasper%2C+J">Justin Kasper</a>, <a href="/search/physics?searchtype=author&query=Whittlesey%2C+P">Phyllis Whittlesey</a>, <a href="/search/physics?searchtype=author&query=MacDowall%2C+R">Robert MacDowall</a>, <a href="/search/physics?searchtype=author&query=Larson%2C+D">Davin Larson</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2310.12134v1-abstract-short" style="display: inline;"> Switchbacks are sudden and large deflections in the magnetic field that Parker Solar Probe frequently observes in the inner heliosphere. Their ubiquitous occurrence has prompted numerous studies to determine their nature and origin. Our goal is to describe the boundary of these switchbacks using a series of events detected during the spacecraft's first encounter with the Sun. Using FIELDS and SWEA… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2310.12134v1-abstract-full').style.display = 'inline'; document.getElementById('2310.12134v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2310.12134v1-abstract-full" style="display: none;"> Switchbacks are sudden and large deflections in the magnetic field that Parker Solar Probe frequently observes in the inner heliosphere. Their ubiquitous occurrence has prompted numerous studies to determine their nature and origin. Our goal is to describe the boundary of these switchbacks using a series of events detected during the spacecraft's first encounter with the Sun. Using FIELDS and SWEAP data, we investigate different methods for determining the boundary normal. The observed boundaries are arc-polarized structures with a rotation that is always contained in a plane. Classical minimum variance analysis (MVA) gives misleading results and overestimates the number of rotational discontinuities. We propose a robust geometric method to identify the nature of these discontinuities, which involves determining whether or not the plane that contains them also includes the origin ($\textbf{B}=0$). Most boundaries appear to have the same characteristics as tangential discontinuities in the context of switchbacks, with little evidence for having rotational discontinuities. We find no effect of the size of the Parker spiral deviation. Furthermore, the thickness of the boundary is within MHD scales. We conclude that most of the switchback boundaries observed by Parker Solar Probe are likely to be closed, in contrast to previous studies. Our results suggest that their erosion may be much slower than expected. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2310.12134v1-abstract-full').style.display = 'none'; document.getElementById('2310.12134v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 18 October, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> October 2023. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">11 pages, 6 figures, Animations available at https://doi.org/10.5281/zenodo.8424748</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> ApJ 958 23 (2023) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2306.04773">arXiv:2306.04773</a> <span> [<a href="https://arxiv.org/pdf/2306.04773">pdf</a>, <a href="https://arxiv.org/format/2306.04773">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Space Physics">physics.space-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Solar and Stellar Astrophysics">astro-ph.SR</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Plasma Physics">physics.plasm-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.3847/1538-4357/ace694">10.3847/1538-4357/ace694 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> The Temperature, Electron, and Pressure Characteristics of Switchbacks: Parker Solar Probe Observations </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Huang%2C+J">Jia Huang</a>, <a href="/search/physics?searchtype=author&query=Kasper%2C+J+C">Justin C. Kasper</a>, <a href="/search/physics?searchtype=author&query=Larson%2C+D+E">Davin E. Larson</a>, <a href="/search/physics?searchtype=author&query=McManus%2C+M+D">Michael D. McManus</a>, <a href="/search/physics?searchtype=author&query=Whittlesey%2C+P">Phyllis Whittlesey</a>, <a href="/search/physics?searchtype=author&query=Livi%2C+R">Roberto Livi</a>, <a href="/search/physics?searchtype=author&query=Rahmati%2C+A">Ali Rahmati</a>, <a href="/search/physics?searchtype=author&query=Romeo%2C+O+M">Orlando M. Romeo</a>, <a href="/search/physics?searchtype=author&query=Liu%2C+M">Mingzhe Liu</a>, <a href="/search/physics?searchtype=author&query=Jian%2C+L+K">Lan K. Jian</a>, <a href="/search/physics?searchtype=author&query=Verniero%2C+J+L">J. L. Verniero</a>, <a href="/search/physics?searchtype=author&query=Velli%2C+M">Marco Velli</a>, <a href="/search/physics?searchtype=author&query=Badman%2C+S+T">Samuel T. Badman</a>, <a href="/search/physics?searchtype=author&query=Rivera%2C+Y+J">Yeimy J. Rivera</a>, <a href="/search/physics?searchtype=author&query=Niembro%2C+T">Tatiana Niembro</a>, <a href="/search/physics?searchtype=author&query=Paulson%2C+K">Kristoff Paulson</a>, <a href="/search/physics?searchtype=author&query=Stevens%2C+M+L">Michael L. Stevens</a>, <a href="/search/physics?searchtype=author&query=Case%2C+A+W">Anthony W. Case</a>, <a href="/search/physics?searchtype=author&query=Bowen%2C+T+A">Trevor A. Bowen</a>, <a href="/search/physics?searchtype=author&query=Pulupa%2C+M">Marc Pulupa</a>, <a href="/search/physics?searchtype=author&query=Bale%2C+S+D">Stuart D. Bale</a>, <a href="/search/physics?searchtype=author&query=Halekas%2C+J+S">Jasper S. Halekas</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2306.04773v2-abstract-short" style="display: inline;"> Parker Solar Probe (PSP) observes unexpectedly prevalent switchbacks, which are rapid magnetic field reversals that last from seconds to hours, in the inner heliosphere, posing new challenges to understanding their nature, origin, and evolution. In this work, we investigate the thermal states, electron pitch angle distributions, and pressure signatures of both inside and outside switchbacks, separ… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2306.04773v2-abstract-full').style.display = 'inline'; document.getElementById('2306.04773v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2306.04773v2-abstract-full" style="display: none;"> Parker Solar Probe (PSP) observes unexpectedly prevalent switchbacks, which are rapid magnetic field reversals that last from seconds to hours, in the inner heliosphere, posing new challenges to understanding their nature, origin, and evolution. In this work, we investigate the thermal states, electron pitch angle distributions, and pressure signatures of both inside and outside switchbacks, separating a switchback into spike, transition region (TR), and quiet period (QP). Based on our analysis, we find that the proton temperature anisotropies in TRs seem to show an intermediate state between spike and QP plasmas. The proton temperatures are more enhanced in spike than in TR and QP, but the alpha temperatures and alpha-to-proton temperature ratios show the opposite trends, implying that the preferential heating mechanisms of protons and alphas are competing in different regions of switchbacks. Moreover, our results suggest that the electron integrated intensities are almost the same across the switchbacks but the electron pitch angle distributions are more isotropic inside than outside switchbacks, implying switchbacks are intact structures but strong scattering of electrons happens inside switchbacks. In addition, the examination of pressures reveals that the total pressures are comparable through an individual switchback, confirming switchbacks are pressure-balanced structures. These characteristics could further our understanding of ion heating, electron scattering, and the structure of switchbacks. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2306.04773v2-abstract-full').style.display = 'none'; document.getElementById('2306.04773v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 29 August, 2023; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 7 June, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> June 2023. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">published in ApJ</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> ApJ 954 133 (2023) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2303.00843">arXiv:2303.00843</a> <span> [<a href="https://arxiv.org/pdf/2303.00843">pdf</a>, <a href="https://arxiv.org/format/2303.00843">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Solar and Stellar Astrophysics">astro-ph.SR</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Fluid Dynamics">physics.flu-dyn</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Geophysics">physics.geo-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Plasma Physics">physics.plasm-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Space Physics">physics.space-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.3847/2041-8213/acd7f2">10.3847/2041-8213/acd7f2 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> New Observations of Solar Wind 1/f Turbulence Spectrum from Parker Solar Probe </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Huang%2C+Z">Zesen Huang</a>, <a href="/search/physics?searchtype=author&query=Sioulas%2C+N">Nikos Sioulas</a>, <a href="/search/physics?searchtype=author&query=Shi%2C+C">Chen Shi</a>, <a href="/search/physics?searchtype=author&query=Velli%2C+M">Marco Velli</a>, <a href="/search/physics?searchtype=author&query=Bowen%2C+T">Trevor Bowen</a>, <a href="/search/physics?searchtype=author&query=Davis%2C+N">Nooshin Davis</a>, <a href="/search/physics?searchtype=author&query=Chandran%2C+B+D+G">B. D. G. Chandran</a>, <a href="/search/physics?searchtype=author&query=Kang%2C+N">Ning Kang</a>, <a href="/search/physics?searchtype=author&query=Shi%2C+X">Xiaofei Shi</a>, <a href="/search/physics?searchtype=author&query=Huang%2C+J">Jia Huang</a>, <a href="/search/physics?searchtype=author&query=Bale%2C+S+D">Stuart D. Bale</a>, <a href="/search/physics?searchtype=author&query=Kasper%2C+J+C">J. C. Kasper</a>, <a href="/search/physics?searchtype=author&query=Larson%2C+D+E">Davin E. Larson</a>, <a href="/search/physics?searchtype=author&query=Livi%2C+R">Roberto Livi</a>, <a href="/search/physics?searchtype=author&query=Whittlesey%2C+P+L">P. L. Whittlesey</a>, <a href="/search/physics?searchtype=author&query=Rahmati%2C+A">Ali Rahmati</a>, <a href="/search/physics?searchtype=author&query=Paulson%2C+K">Kristoff Paulson</a>, <a href="/search/physics?searchtype=author&query=Stevens%2C+M">M. Stevens</a>, <a href="/search/physics?searchtype=author&query=Case%2C+A+W">A. W. Case</a>, <a href="/search/physics?searchtype=author&query=de+Wit%2C+T+D">Thierry Dudok de Wit</a>, <a href="/search/physics?searchtype=author&query=Malaspina%2C+D+M">David M. Malaspina</a>, <a href="/search/physics?searchtype=author&query=Bonnell%2C+J+W">J. W. Bonnell</a>, <a href="/search/physics?searchtype=author&query=Goetz%2C+K">Keith Goetz</a>, <a href="/search/physics?searchtype=author&query=Harvey%2C+P+R">Peter R. Harvey</a>, <a href="/search/physics?searchtype=author&query=MacDowall%2C+R+J">Robert J. MacDowall</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2303.00843v2-abstract-short" style="display: inline;"> The trace magnetic power spectrum in the solar wind is known to be characterized by a double power law at scales much larger than the proton gyro-radius, with flatter spectral exponents close to -1 found at the lower frequencies below an inertial range with indices closer to $[-1.5,-1.6]$. The origin of the $1/f$ range is still under debate. In this study, we selected 109 magnetically incompressib… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2303.00843v2-abstract-full').style.display = 'inline'; document.getElementById('2303.00843v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2303.00843v2-abstract-full" style="display: none;"> The trace magnetic power spectrum in the solar wind is known to be characterized by a double power law at scales much larger than the proton gyro-radius, with flatter spectral exponents close to -1 found at the lower frequencies below an inertial range with indices closer to $[-1.5,-1.6]$. The origin of the $1/f$ range is still under debate. In this study, we selected 109 magnetically incompressible solar wind intervals ($未|\boldsymbol B|/|\boldsymbol B| \ll 1$) from Parker Solar Probe encounters 1 to 13 which display such double power laws, with the aim of understanding the statistics and radial evolution of the low frequency power spectral exponents from Alfv茅n point up to 0.3 AU. New observations from closer to the sun show that in the low frequency range solar wind turbulence can display spectra much shallower than $1/f$, evolving asymptotically to $1/f$ as advection time increases, indicating a dynamic origin for the $1/f$ range formation. We discuss the implications of this result on the Matteini et al. (2018) conjecture for the $1/f$ origin as well as example spectra displaying a triple power law consistent with the model proposed by Chandran et al. (2018), supporting the dynamic role of parametric decay in the young solar wind. Our results provide new constraints on the origin of the $1/f$ spectrum and further show the possibility of the coexistence of multiple formation mechanisms. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2303.00843v2-abstract-full').style.display = 'none'; document.getElementById('2303.00843v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 23 May, 2023; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 1 March, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> March 2023. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">Accepted by ApJL</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2302.07230">arXiv:2302.07230</a> <span> [<a href="https://arxiv.org/pdf/2302.07230">pdf</a>, <a href="https://arxiv.org/format/2302.07230">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Space Physics">physics.space-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.3847/1538-4365/acbcd2">10.3847/1538-4365/acbcd2 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Parker Solar Probe Observations of High Plasma Beta Solar Wind from Streamer Belt </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Huang%2C+J">Jia Huang</a>, <a href="/search/physics?searchtype=author&query=Kasper%2C+J+C">J. C. Kasper</a>, <a href="/search/physics?searchtype=author&query=Larson%2C+D+E">Davin E. Larson</a>, <a href="/search/physics?searchtype=author&query=McManus%2C+M+D">Michael D. McManus</a>, <a href="/search/physics?searchtype=author&query=Whittlesey%2C+P">P. Whittlesey</a>, <a href="/search/physics?searchtype=author&query=Livi%2C+R">Roberto Livi</a>, <a href="/search/physics?searchtype=author&query=Rahmati%2C+A">Ali Rahmati</a>, <a href="/search/physics?searchtype=author&query=Romeo%2C+O">Orlando Romeo</a>, <a href="/search/physics?searchtype=author&query=Klein%2C+K+G">K. G. Klein</a>, <a href="/search/physics?searchtype=author&query=Sun%2C+W">Weijie Sun</a>, <a href="/search/physics?searchtype=author&query=van+der+Holst%2C+B">Bart van der Holst</a>, <a href="/search/physics?searchtype=author&query=Huang%2C+Z">Zhenguang Huang</a>, <a href="/search/physics?searchtype=author&query=Jian%2C+L+K">Lan K. Jian</a>, <a href="/search/physics?searchtype=author&query=Szabo%2C+A">Adam Szabo</a>, <a href="/search/physics?searchtype=author&query=Verniero%2C+J+L">J. L. Verniero</a>, <a href="/search/physics?searchtype=author&query=Chen%2C+C+H+K">C. H. K. Chen</a>, <a href="/search/physics?searchtype=author&query=Lavraud%2C+B">B. Lavraud</a>, <a href="/search/physics?searchtype=author&query=Liu%2C+M">Mingzhe Liu</a>, <a href="/search/physics?searchtype=author&query=Badman%2C+S+T">Samuel T. Badman</a>, <a href="/search/physics?searchtype=author&query=Niembro%2C+T">Tatiana Niembro</a>, <a href="/search/physics?searchtype=author&query=Paulson%2C+K">Kristoff Paulson</a>, <a href="/search/physics?searchtype=author&query=Stevens%2C+M">M. Stevens</a>, <a href="/search/physics?searchtype=author&query=Case%2C+A+W">A. W. Case</a>, <a href="/search/physics?searchtype=author&query=Pulupa%2C+M">Marc Pulupa</a>, <a href="/search/physics?searchtype=author&query=Bale%2C+S+D">Stuart D. Bale</a> , et al. (1 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2302.07230v1-abstract-short" style="display: inline;"> In general, slow solar wind from the streamer belt forms a high plasma beta equatorial plasma sheet around the heliospheric current sheet (HCS) crossing, namely the heliospheric plasma sheet (HPS). Current Parker Solar Probe (PSP) observations show that the HCS crossings near the Sun could be full or partial current sheet crossing (PCS), and they share some common features but also have different… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2302.07230v1-abstract-full').style.display = 'inline'; document.getElementById('2302.07230v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2302.07230v1-abstract-full" style="display: none;"> In general, slow solar wind from the streamer belt forms a high plasma beta equatorial plasma sheet around the heliospheric current sheet (HCS) crossing, namely the heliospheric plasma sheet (HPS). Current Parker Solar Probe (PSP) observations show that the HCS crossings near the Sun could be full or partial current sheet crossing (PCS), and they share some common features but also have different properties. In this work, using the PSP observations from encounters 4 to 10, we identify streamer belt solar wind from enhancements in plasma beta, and we further use electron pitch angle distributions to separate it into HPS solar wind that around the full HCS crossings and PCS solar wind that in the vicinity of PCS crossings. Based on our analysis, we find that the PCS solar wind has different characteristics as compared with HPS solar wind: a) PCS solar wind could be non-pressure-balanced structures rather than magnetic holes, and the total pressure enhancement mainly results from the less reduced magnetic pressure; b) some of the PCS solar wind are mirror unstable; c) PCS solar wind is dominated by very low helium abundance but varied alpha-proton differential speed. We suggest the PCS solar wind could originate from coronal loops deep inside the streamer belt, and it is pristine solar wind that still actively interacts with ambient solar wind, thus it is valuable for further investigations on the heating and acceleration of slow solar wind. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2302.07230v1-abstract-full').style.display = 'none'; document.getElementById('2302.07230v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 14 February, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> February 2023. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2301.10374">arXiv:2301.10374</a> <span> [<a href="https://arxiv.org/pdf/2301.10374">pdf</a>, <a href="https://arxiv.org/format/2301.10374">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Space Physics">physics.space-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Solar and Stellar Astrophysics">astro-ph.SR</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.3847/1538-4357/acd17e">10.3847/1538-4357/acd17e <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> The Structure and Origin of Switchbacks: Parker Solar Probe Observations </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Huang%2C+J">Jia Huang</a>, <a href="/search/physics?searchtype=author&query=Kasper%2C+J+C">J. C. Kasper</a>, <a href="/search/physics?searchtype=author&query=Fisk%2C+L+A">L. A. Fisk</a>, <a href="/search/physics?searchtype=author&query=Larson%2C+D+E">Davin E. Larson</a>, <a href="/search/physics?searchtype=author&query=McManus%2C+M+D">Michael D. McManus</a>, <a href="/search/physics?searchtype=author&query=Chen%2C+C+H+K">C. H. K. Chen</a>, <a href="/search/physics?searchtype=author&query=Martinovi%C4%87%2C+M+M">Mihailo M. Martinovi膰</a>, <a href="/search/physics?searchtype=author&query=Klein%2C+K+G">K. G. Klein</a>, <a href="/search/physics?searchtype=author&query=Thomas%2C+L">Luke Thomas</a>, <a href="/search/physics?searchtype=author&query=Liu%2C+M">Mingzhe Liu</a>, <a href="/search/physics?searchtype=author&query=Maruca%2C+B+A">Bennett A. Maruca</a>, <a href="/search/physics?searchtype=author&query=Zhao%2C+L">Lingling Zhao</a>, <a href="/search/physics?searchtype=author&query=Chen%2C+Y">Yu Chen</a>, <a href="/search/physics?searchtype=author&query=Hu%2C+Q">Qiang Hu</a>, <a href="/search/physics?searchtype=author&query=Jian%2C+L+K">Lan K. Jian</a>, <a href="/search/physics?searchtype=author&query=Verniero%2C+J+L">J. L. Verniero</a>, <a href="/search/physics?searchtype=author&query=Velli%2C+M">Marco Velli</a>, <a href="/search/physics?searchtype=author&query=Livi%2C+R">Roberto Livi</a>, <a href="/search/physics?searchtype=author&query=Whittlesey%2C+P">P. Whittlesey</a>, <a href="/search/physics?searchtype=author&query=Rahmati%2C+A">Ali Rahmati</a>, <a href="/search/physics?searchtype=author&query=Romeo%2C+O">Orlando Romeo</a>, <a href="/search/physics?searchtype=author&query=Niembro%2C+T">Tatiana Niembro</a>, <a href="/search/physics?searchtype=author&query=Paulson%2C+K">Kristoff Paulson</a>, <a href="/search/physics?searchtype=author&query=Stevens%2C+M">M. Stevens</a>, <a href="/search/physics?searchtype=author&query=Case%2C+A+W">A. W. Case</a> , et al. (3 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2301.10374v3-abstract-short" style="display: inline;"> Switchbacks are rapid magnetic field reversals that last from seconds to hours. Current Parker Solar Probe (PSP) observations pose many open questions in regard to the nature of switchbacks. For example, are they stable as they propagate through the inner heliosphere, and how are they formed? In this work, we aim to investigate the structure and origin of switchbacks. In order to study the stabili… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2301.10374v3-abstract-full').style.display = 'inline'; document.getElementById('2301.10374v3-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2301.10374v3-abstract-full" style="display: none;"> Switchbacks are rapid magnetic field reversals that last from seconds to hours. Current Parker Solar Probe (PSP) observations pose many open questions in regard to the nature of switchbacks. For example, are they stable as they propagate through the inner heliosphere, and how are they formed? In this work, we aim to investigate the structure and origin of switchbacks. In order to study the stability of switchbacks, we suppose the small-scale current sheets therein are generated by magnetic braiding, and they should work to stabilize the switchbacks. With more than one thousand switchbacks identified with PSP observations in seven encounters, we find many more current sheets inside than outside switchbacks, indicating that these microstructures should work to stabilize the S-shaped structures of switchbacks. Additionally, we study the helium variations to trace the switchbacks to their origins. We find both helium-rich and helium-poor populations in switchbacks, implying that the switchbacks could originate from both closed and open magnetic field regions in the Sun. Moreover, we observe that the alpha-proton differential speeds also show complex variations as compared to the local Alfv茅n speed. The joint distributions of both parameters show that low helium abundance together with low differential speed is the dominant state in switchbacks. The presence of small-scale current sheets in switchbacks along with the helium features are in line with the hypothesis that switchbacks could originate from the Sun via interchange reconnection process. However, other formation mechanisms are not excluded. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2301.10374v3-abstract-full').style.display = 'none'; document.getElementById('2301.10374v3-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 22 May, 2023; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 24 January, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> January 2023. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">accepted by ApJ</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2207.06563">arXiv:2207.06563</a> <span> [<a href="https://arxiv.org/pdf/2207.06563">pdf</a>, <a href="https://arxiv.org/format/2207.06563">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Solar and Stellar Astrophysics">astro-ph.SR</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Plasma Physics">physics.plasm-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Space Physics">physics.space-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.3847/1538-4357/ac85b8">10.3847/1538-4357/ac85b8 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> The Radial Evolution of the Solar Wind as Organized by Electron Distribution Parameters </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Halekas%2C+J+S">J. S. Halekas</a>, <a href="/search/physics?searchtype=author&query=Whittlesey%2C+P">P. Whittlesey</a>, <a href="/search/physics?searchtype=author&query=Larson%2C+D+E">D. E. Larson</a>, <a href="/search/physics?searchtype=author&query=Maksimovic%2C+M">M. Maksimovic</a>, <a href="/search/physics?searchtype=author&query=Livi%2C+R">R. Livi</a>, <a href="/search/physics?searchtype=author&query=Berthomier%2C+M">M. Berthomier</a>, <a href="/search/physics?searchtype=author&query=Kasper%2C+J+C">J. C. Kasper</a>, <a href="/search/physics?searchtype=author&query=Case%2C+A+W">A. W. Case</a>, <a href="/search/physics?searchtype=author&query=Stevens%2C+M+L">M. L. Stevens</a>, <a href="/search/physics?searchtype=author&query=Bale%2C+S+D">S. D. Bale</a>, <a href="/search/physics?searchtype=author&query=MacDowall%2C+R+J">R. J. MacDowall</a>, <a href="/search/physics?searchtype=author&query=Pulupa%2C+M+P">M. P. Pulupa</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2207.06563v1-abstract-short" style="display: inline;"> We utilize observations from the Parker Solar Probe (PSP) to study the radial evolution of the solar wind in the inner heliosphere. We analyze electron velocity distribution functions observed by the Solar Wind Electrons, Alphas, and Protons suite to estimate the coronal electron temperature and the local electric potential in the solar wind. From the latter value and the local flow speed, we comp… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2207.06563v1-abstract-full').style.display = 'inline'; document.getElementById('2207.06563v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2207.06563v1-abstract-full" style="display: none;"> We utilize observations from the Parker Solar Probe (PSP) to study the radial evolution of the solar wind in the inner heliosphere. We analyze electron velocity distribution functions observed by the Solar Wind Electrons, Alphas, and Protons suite to estimate the coronal electron temperature and the local electric potential in the solar wind. From the latter value and the local flow speed, we compute the asymptotic solar wind speed. We group the PSP observations by asymptotic speed, and characterize the radial evolution of the wind speed, electron temperature, and electric potential within each group. In agreement with previous work, we find that the electron temperature (both local and coronal) and the electric potential are anti-correlated with wind speed. This implies that the electron thermal pressure and the associated electric field can provide more net acceleration in the slow wind than in the fast wind. We then utilize the inferred coronal temperature and the extrapolated electric + gravitational potential to show that both electric field driven exospheric models and the equivalent thermally driven hydrodynamic models can explain the entire observed speed of the slowest solar wind streams. On the other hand, neither class of model can explain the observed speed of the faster solar wind streams, which thus require additional acceleration mechanisms. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2207.06563v1-abstract-full').style.display = 'none'; document.getElementById('2207.06563v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 13 July, 2022; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> July 2022. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">Submitted to the Astrophysical Journal</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2201.10718">arXiv:2201.10718</a> <span> [<a href="https://arxiv.org/pdf/2201.10718">pdf</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Space Physics">physics.space-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Solar and Stellar Astrophysics">astro-ph.SR</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Plasma Physics">physics.plasm-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.3847/2041-8213/ac4a5c">10.3847/2041-8213/ac4a5c <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Sub-Alfvenic Solar Wind observed by PSP: Characterization of Turbulence, Anisotropy, Intermittency, and Switchback </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Bandyopadhyay%2C+R">R. Bandyopadhyay</a>, <a href="/search/physics?searchtype=author&query=Matthaeus%2C+W+H">W. H. Matthaeus</a>, <a href="/search/physics?searchtype=author&query=McComas%2C+D+J">D. J. McComas</a>, <a href="/search/physics?searchtype=author&query=Chhiber%2C+R">R. Chhiber</a>, <a href="/search/physics?searchtype=author&query=Usmanov%2C+A+V">A. V. Usmanov</a>, <a href="/search/physics?searchtype=author&query=Huang%2C+J">J. Huang</a>, <a href="/search/physics?searchtype=author&query=Livi%2C+R">R. Livi</a>, <a href="/search/physics?searchtype=author&query=Larson%2C+D+E">D. E. Larson</a>, <a href="/search/physics?searchtype=author&query=Kasper%2C+J+C">J. C. Kasper</a>, <a href="/search/physics?searchtype=author&query=Case%2C+A+W">A. W. Case</a>, <a href="/search/physics?searchtype=author&query=Stevens%2C+M">M. Stevens</a>, <a href="/search/physics?searchtype=author&query=Whittlesey%2C+P">P. Whittlesey</a>, <a href="/search/physics?searchtype=author&query=Romeo%2C+O+M">O. M. Romeo</a>, <a href="/search/physics?searchtype=author&query=Bale%2C+S+D">S. D. Bale</a>, <a href="/search/physics?searchtype=author&query=Bonnell%2C+J+W">J. W. Bonnell</a>, <a href="/search/physics?searchtype=author&query=de+Wit%2C+T+D">T. Dudok de Wit</a>, <a href="/search/physics?searchtype=author&query=Goetz%2C+K">K. Goetz</a>, <a href="/search/physics?searchtype=author&query=Harvey%2C+P+R">P. R. Harvey</a>, <a href="/search/physics?searchtype=author&query=MacDowall%2C+R+J">R. J. MacDowall</a>, <a href="/search/physics?searchtype=author&query=Malaspina%2C+D+M">D. M. Malaspina</a>, <a href="/search/physics?searchtype=author&query=Pulupa%2C+M">M. Pulupa</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2201.10718v1-abstract-short" style="display: inline;"> In the lower solar coronal regions where the magnetic field is dominant, the Alfven speed is much higher than the wind speed. In contrast, the near-Earth solar wind is strongly super-Alfvenic, i.e., the wind speed greatly exceeds the Alfven speed. The transition between these regimes is classically described as the "Alfven point" but may in fact occur in a distributed Alfven critical region. NASA'… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2201.10718v1-abstract-full').style.display = 'inline'; document.getElementById('2201.10718v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2201.10718v1-abstract-full" style="display: none;"> In the lower solar coronal regions where the magnetic field is dominant, the Alfven speed is much higher than the wind speed. In contrast, the near-Earth solar wind is strongly super-Alfvenic, i.e., the wind speed greatly exceeds the Alfven speed. The transition between these regimes is classically described as the "Alfven point" but may in fact occur in a distributed Alfven critical region. NASA's Parker Solar Probe (PSP) mission has entered this region, as it follows a series of orbits that gradually approach more closely to the sun. During its 8th and 9th solar encounters, at a distance of 16 solar radii from the Sun, PSP sampled four extended periods in which the solar wind speed was measured to be smaller than the local Alfven speed. These are the first in-situ detections of sub-Alfvenic solar wind in the inner heliosphere by PSP. Here we explore properties of these samples of sub-Alfvenic solar wind, which may provide important previews of the physical processes operating at lower altitude. Specifically, we characterize the turbulence, anisotropy, intermittency, and directional switchback properties of these sub-Alfvenic winds and contrast these with the neighboring super-Alfvenic periods. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2201.10718v1-abstract-full').style.display = 'none'; document.getElementById('2201.10718v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 25 January, 2022; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> January 2022. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">Accepted for publication in the Astrophysical Journal Letter</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2110.11031">arXiv:2110.11031</a> <span> [<a href="https://arxiv.org/pdf/2110.11031">pdf</a>, <a href="https://arxiv.org/format/2110.11031">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Solar and Stellar Astrophysics">astro-ph.SR</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Plasma Physics">physics.plasm-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Space Physics">physics.space-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.3847/2041-8213/ac282f">10.3847/2041-8213/ac282f <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Exploring the Solar Wind from its Source on the Corona into the Inner Heliosphere during the First Solar Orbiter - Parker Solar Probe Quadrature </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Telloni%2C+D">Daniele Telloni</a>, <a href="/search/physics?searchtype=author&query=Andretta%2C+V">Vincenzo Andretta</a>, <a href="/search/physics?searchtype=author&query=Antonucci%2C+E">Ester Antonucci</a>, <a href="/search/physics?searchtype=author&query=Bemporad%2C+A">Alessandro Bemporad</a>, <a href="/search/physics?searchtype=author&query=Capuano%2C+G+E">Giuseppe E. Capuano</a>, <a href="/search/physics?searchtype=author&query=Fineschi%2C+S">Silvano Fineschi</a>, <a href="/search/physics?searchtype=author&query=Giordano%2C+S">Silvio Giordano</a>, <a href="/search/physics?searchtype=author&query=Habbal%2C+S">Shadia Habbal</a>, <a href="/search/physics?searchtype=author&query=Perrone%2C+D">Denise Perrone</a>, <a href="/search/physics?searchtype=author&query=Pinto%2C+R+F">Rui F. Pinto</a>, <a href="/search/physics?searchtype=author&query=Sorriso-Valvo%2C+L">Luca Sorriso-Valvo</a>, <a href="/search/physics?searchtype=author&query=Spadaro%2C+D">Daniele Spadaro</a>, <a href="/search/physics?searchtype=author&query=Susino%2C+R">Roberto Susino</a>, <a href="/search/physics?searchtype=author&query=Woodham%2C+L+D">Lloyd D. Woodham</a>, <a href="/search/physics?searchtype=author&query=Zank%2C+G+P">Gary P. Zank</a>, <a href="/search/physics?searchtype=author&query=Romoli%2C+M">Marco Romoli</a>, <a href="/search/physics?searchtype=author&query=Bale%2C+S+D">Stuart D. Bale</a>, <a href="/search/physics?searchtype=author&query=Kasper%2C+J+C">Justin C. Kasper</a>, <a href="/search/physics?searchtype=author&query=Auch%C3%A8re%2C+F">Fr茅d茅ric Auch猫re</a>, <a href="/search/physics?searchtype=author&query=Bruno%2C+R">Roberto Bruno</a>, <a href="/search/physics?searchtype=author&query=Capobianco%2C+G">Gerardo Capobianco</a>, <a href="/search/physics?searchtype=author&query=Case%2C+A+W">Anthony W. Case</a>, <a href="/search/physics?searchtype=author&query=Casini%2C+C">Chiara Casini</a>, <a href="/search/physics?searchtype=author&query=Casti%2C+M">Marta Casti</a>, <a href="/search/physics?searchtype=author&query=Chioetto%2C+P">Paolo Chioetto</a> , et al. (46 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2110.11031v1-abstract-short" style="display: inline;"> This Letter addresses the first Solar Orbiter (SO) -- Parker Solar Probe (PSP) quadrature, occurring on January 18, 2021, to investigate the evolution of solar wind from the extended corona to the inner heliosphere. Assuming ballistic propagation, the same plasma volume observed remotely in corona at altitudes between 3.5 and 6.3 solar radii above the solar limb with the Metis coronagraph on SO ca… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2110.11031v1-abstract-full').style.display = 'inline'; document.getElementById('2110.11031v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2110.11031v1-abstract-full" style="display: none;"> This Letter addresses the first Solar Orbiter (SO) -- Parker Solar Probe (PSP) quadrature, occurring on January 18, 2021, to investigate the evolution of solar wind from the extended corona to the inner heliosphere. Assuming ballistic propagation, the same plasma volume observed remotely in corona at altitudes between 3.5 and 6.3 solar radii above the solar limb with the Metis coronagraph on SO can be tracked to PSP, orbiting at 0.1 au, thus allowing the local properties of the solar wind to be linked to the coronal source region from where it originated. Thanks to the close approach of PSP to the Sun and the simultaneous Metis observation of the solar corona, the flow-aligned magnetic field and the bulk kinetic energy flux density can be empirically inferred along the coronal current sheet with an unprecedented accuracy, allowing in particular estimation of the Alfv茅n radius at 8.7 solar radii during the time of this event. This is thus the very first study of the same solar wind plasma as it expands from the sub-Alfv茅nic solar corona to just above the Alfv茅n surface. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2110.11031v1-abstract-full').style.display = 'none'; document.getElementById('2110.11031v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 21 October, 2021; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> October 2021. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">10 pages, 4 figures</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Telloni, D., Andretta, V., Antonucci, E., et al. 2021, ApJL, 920, L14 </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2108.08528">arXiv:2108.08528</a> <span> [<a href="https://arxiv.org/pdf/2108.08528">pdf</a>, <a href="https://arxiv.org/format/2108.08528">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Solar and Stellar Astrophysics">astro-ph.SR</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Plasma Physics">physics.plasm-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Space Physics">physics.space-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.3847/1538-4357/ac1f1c">10.3847/1538-4357/ac1f1c <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Ambipolar electric field and potential in the solar wind estimated from electron velocity distribution functions </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Bercic%2C+L">Laura Bercic</a>, <a href="/search/physics?searchtype=author&query=Maksimovic%2C+M">Milan Maksimovic</a>, <a href="/search/physics?searchtype=author&query=Halekas%2C+J+S">Jasper S. Halekas</a>, <a href="/search/physics?searchtype=author&query=Landi%2C+S">Smone Landi</a>, <a href="/search/physics?searchtype=author&query=Owen%2C+C+J">Christopher J. Owen</a>, <a href="/search/physics?searchtype=author&query=Verscharen%2C+D">Daniel Verscharen</a>, <a href="/search/physics?searchtype=author&query=Larson%2C+D">Davin Larson</a>, <a href="/search/physics?searchtype=author&query=Whittlesey%2C+P">Phyllis Whittlesey</a>, <a href="/search/physics?searchtype=author&query=Badman%2C+S+T">Samuel T. Badman</a>, <a href="/search/physics?searchtype=author&query=Bale%2C+S+D">Stuart. D. Bale</a>, <a href="/search/physics?searchtype=author&query=Case%2C+A+W">Anthony W. Case</a>, <a href="/search/physics?searchtype=author&query=Goetz%2C+K">Keith Goetz</a>, <a href="/search/physics?searchtype=author&query=Harvey%2C+P+R">Peter R. Harvey</a>, <a href="/search/physics?searchtype=author&query=Kasper%2C+J+C">Justin C. Kasper</a>, <a href="/search/physics?searchtype=author&query=Korreck%2C+K+E">Kelly E. Korreck</a>, <a href="/search/physics?searchtype=author&query=Livi%2C+R">Roberto Livi</a>, <a href="/search/physics?searchtype=author&query=MacDowall%2C+R+J">Robert J. MacDowall</a>, <a href="/search/physics?searchtype=author&query=Malaspina%2C+D+M">David M. Malaspina</a>, <a href="/search/physics?searchtype=author&query=Pulupa%2C+M">Marc Pulupa</a>, <a href="/search/physics?searchtype=author&query=Stevens%2C+M+L">Michael L. Stevens</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2108.08528v1-abstract-short" style="display: inline;"> The solar wind escapes from the solar corona and is accelerated, over a short distance, to its terminal velocity. The energy balance associated with this acceleration remains poorly understood. To quantify the global electrostatic contribution to the solar wind dynamics, we empirically estimate the ambipolar electric field ($\mathrm{E}_\parallel$) and potential ($桅_\mathrm{r,\infty}$). We analyse… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2108.08528v1-abstract-full').style.display = 'inline'; document.getElementById('2108.08528v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2108.08528v1-abstract-full" style="display: none;"> The solar wind escapes from the solar corona and is accelerated, over a short distance, to its terminal velocity. The energy balance associated with this acceleration remains poorly understood. To quantify the global electrostatic contribution to the solar wind dynamics, we empirically estimate the ambipolar electric field ($\mathrm{E}_\parallel$) and potential ($桅_\mathrm{r,\infty}$). We analyse electron velocity distribution functions (VDFs) measured in the near-Sun solar wind, between 20.3\,$R_S$ and 85.3\,$R_S$, by the Parker Solar Probe. We test the predictions of two different solar wind models. Close to the Sun, the VDFs exhibit a suprathermal electron deficit in the sunward, magnetic field aligned part of phase space. We argue that the sunward deficit is a remnant of the electron cutoff predicted by collisionless exospheric models (Lemaire & Sherer 1970, 1971, Jockers 1970). This cutoff energy is directly linked to $桅_\mathrm{r,\infty}$. Competing effects of $\mathrm{E}_\parallel$ and Coulomb collisions in the solar wind are addressed by the Steady Electron Runaway Model (SERM) (Scudder 2019). In this model, electron phase space is separated into collisionally overdamped and underdamped regions. We assume that this boundary velocity at small pitch angles coincides with the strahl break-point energy, which allows us to calculate $\mathrm{E}_\parallel$. The obtained $桅_\mathrm{r,\infty}$ and $\mathrm{E}_\parallel$ agree well with theoretical expectations. They decrease with radial distance as power law functions with indices $伪_桅= -0.66$ and $伪_\mathrm{E} = -1.69$. We finally estimate the velocity gained by protons from electrostatic acceleration, which equals to 77\% calculated from the exospheric models, and to 44\% from the SERM model. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2108.08528v1-abstract-full').style.display = 'none'; document.getElementById('2108.08528v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 19 August, 2021; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> August 2021. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2105.08651">arXiv:2105.08651</a> <span> [<a href="https://arxiv.org/pdf/2105.08651">pdf</a>, <a href="https://arxiv.org/format/2105.08651">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Space Physics">physics.space-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Instrumentation and Methods for Astrophysics">astro-ph.IM</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Plasma Physics">physics.plasm-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1051/0004-6361/202141063">10.1051/0004-6361/202141063 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> A powerful machine learning technique to extract proton core, beam and alpha-particle parameters from velocity distribution functions in space plasmas </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Vech%2C+D">Daniel Vech</a>, <a href="/search/physics?searchtype=author&query=Stevens%2C+M+L">Michael L. Stevens</a>, <a href="/search/physics?searchtype=author&query=Paulson%2C+K+W">Kristoff W. Paulson</a>, <a href="/search/physics?searchtype=author&query=Malaspina%2C+D+M">David M. Malaspina</a>, <a href="/search/physics?searchtype=author&query=Case%2C+A+W">Anthony W. Case</a>, <a href="/search/physics?searchtype=author&query=Klein%2C+K+G">Kristopher G. Klein</a>, <a href="/search/physics?searchtype=author&query=Kasper%2C+J+C">Justin C. Kasper</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2105.08651v1-abstract-short" style="display: inline;"> Context: The analysis of the thermal part of velocity distribution functions (VDF) is fundamentally important for understanding the kinetic physics that governs the evolution and dynamics of space plasmas. However, calculating the proton core, beam and alpha-particle parameters for large data sets of VDFs is a time consuming and computationally demanding process that always requires supervision by… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2105.08651v1-abstract-full').style.display = 'inline'; document.getElementById('2105.08651v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2105.08651v1-abstract-full" style="display: none;"> Context: The analysis of the thermal part of velocity distribution functions (VDF) is fundamentally important for understanding the kinetic physics that governs the evolution and dynamics of space plasmas. However, calculating the proton core, beam and alpha-particle parameters for large data sets of VDFs is a time consuming and computationally demanding process that always requires supervision by a human expert. Aims: We developed a machine learning tool that can extract proton core, beam and alpha-particle parameters using images (2-D grid consisting pixel values) of VDFs. Methods: A database of synthetic VDFs is generated, which is used to train a convolutional neural network that infers bulk speed, thermal speed and density for all three particle populations. We generate a separate test data set of synthetic VDFs that we use to compare and quantify the predictive power of the neural network and a fitting algorithm. Results: The neural network achieves significantly smaller root-mean-square errors to infer proton core, beam and alpha-particle parameters than a traditional fitting algorithm. Conclusion: The developed machine learning tool has the potential to revolutionize the processing of particle measurements since it allows the computation of more accurate particle parameters than previously used fitting procedures. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2105.08651v1-abstract-full').style.display = 'none'; document.getElementById('2105.08651v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 18 May, 2021; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> May 2021. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">Accepted in Astronomy and Astrophysics</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2103.00374">arXiv:2103.00374</a> <span> [<a href="https://arxiv.org/pdf/2103.00374">pdf</a>, <a href="https://arxiv.org/format/2103.00374">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Solar and Stellar Astrophysics">astro-ph.SR</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Space Physics">physics.space-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.3847/1538-4357/abebe5">10.3847/1538-4357/abebe5 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Multiscale Solar Wind Turbulence Properties inside and near Switchbacks measured by Parker Solar Probe </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Martinovi%C4%87%2C+M+M">Mihailo M. Martinovi膰</a>, <a href="/search/physics?searchtype=author&query=Klein%2C+K+G">Kristopher G. Klein</a>, <a href="/search/physics?searchtype=author&query=Huang%2C+J">Jia Huang</a>, <a href="/search/physics?searchtype=author&query=Chandran%2C+B+D+G">Benjamin D. G. Chandran</a>, <a href="/search/physics?searchtype=author&query=Kasper%2C+J+C">Justin C. Kasper</a>, <a href="/search/physics?searchtype=author&query=Lichko%2C+E">Emily Lichko</a>, <a href="/search/physics?searchtype=author&query=Bowen%2C+T">Trevor Bowen</a>, <a href="/search/physics?searchtype=author&query=Chen%2C+C+H+K">Christopher H. K. Chen</a>, <a href="/search/physics?searchtype=author&query=Matteini%2C+L">Lorenzo Matteini</a>, <a href="/search/physics?searchtype=author&query=Stevens%2C+M">Michael Stevens</a>, <a href="/search/physics?searchtype=author&query=Case%2C+A+W">Anthony W. Case</a>, <a href="/search/physics?searchtype=author&query=Bale%2C+S+D">Stuart D. Bale</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2103.00374v1-abstract-short" style="display: inline;"> Parker Solar Probe (PSP) routinely observes magnetic field deflections in the solar wind at distances less than 0.3 au from the Sun. These deflections are related to structures commonly called 'switchbacks' (SBs), whose origins and characteristic properties are currently debated. Here, we use a database of visually selected SB intervals - and regions of solar wind plasma measured just before and a… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2103.00374v1-abstract-full').style.display = 'inline'; document.getElementById('2103.00374v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2103.00374v1-abstract-full" style="display: none;"> Parker Solar Probe (PSP) routinely observes magnetic field deflections in the solar wind at distances less than 0.3 au from the Sun. These deflections are related to structures commonly called 'switchbacks' (SBs), whose origins and characteristic properties are currently debated. Here, we use a database of visually selected SB intervals - and regions of solar wind plasma measured just before and after each SB - to examine plasma parameters, turbulent spectra from inertial to dissipation scales, and intermittency effects in these intervals. We find that many features, such as perpendicular stochastic heating rates and turbulence spectral slopes are fairly similar inside and outside of SBs. However, important kinetic properties, such as the characteristic break scale between the inertial to dissipation ranges differ inside and outside these intervals, as does the level of intermittency, which is notably enhanced inside SBs and in their close proximity, most likely due to magnetic field and velocity shears observed at the edges. We conclude that the plasma inside and outside of a SB, in most of the observed cases, belongs to the same stream, and that the evolution of these structures is most likely regulated by kinetic processes, which dominate small scale structures at the SB edges. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2103.00374v1-abstract-full').style.display = 'none'; document.getElementById('2103.00374v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 27 February, 2021; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> March 2021. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2101.06723">arXiv:2101.06723</a> <span> [<a href="https://arxiv.org/pdf/2101.06723">pdf</a>, <a href="https://arxiv.org/format/2101.06723">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Space Physics">physics.space-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1051/0004-6361/202039808">10.1051/0004-6361/202039808 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Whistler wave occurrence and the interaction with strahl electrons during the first encounter of Parker Solar Probe </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Jagarlamudi%2C+V+K">V. K. Jagarlamudi</a>, <a href="/search/physics?searchtype=author&query=de+Wit%2C+T+D">T. Dudok de Wit</a>, <a href="/search/physics?searchtype=author&query=Froment%2C+C">C. Froment</a>, <a href="/search/physics?searchtype=author&query=Krasnoselskikh%2C+V">V. Krasnoselskikh</a>, <a href="/search/physics?searchtype=author&query=Larosa%2C+A">A. Larosa</a>, <a href="/search/physics?searchtype=author&query=Bercic%2C+L">L. Bercic</a>, <a href="/search/physics?searchtype=author&query=Agapitov%2C+O">O. Agapitov</a>, <a href="/search/physics?searchtype=author&query=Halekas%2C+J+S">J. S. Halekas</a>, <a href="/search/physics?searchtype=author&query=Kretzschmar%2C+M">M. Kretzschmar</a>, <a href="/search/physics?searchtype=author&query=Malaspina%2C+D">D. Malaspina</a>, <a href="/search/physics?searchtype=author&query=Moncuquet%2C+M">M. Moncuquet</a>, <a href="/search/physics?searchtype=author&query=Bale%2C+S+D">S. D. Bale</a>, <a href="/search/physics?searchtype=author&query=Case%2C+A+W">A. W. Case</a>, <a href="/search/physics?searchtype=author&query=Kasper%2C+J+C">J. C. Kasper</a>, <a href="/search/physics?searchtype=author&query=Korreck%2C+K+E">K. E. Korreck</a>, <a href="/search/physics?searchtype=author&query=Larson%2C+D+E">D. E. Larson</a>, <a href="/search/physics?searchtype=author&query=Pulupa%2C+M">M. Pulupa</a>, <a href="/search/physics?searchtype=author&query=Stevens%2C+M+L">M. L. Stevens</a>, <a href="/search/physics?searchtype=author&query=Whittlesey%2C+P">P. Whittlesey</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2101.06723v2-abstract-short" style="display: inline;"> We studied the properties and occurrence of narrow band whistler waves and their interaction with strahl electrons observed between 0.17 and 0.26 au during the first encounter of Parker Solar Probe. We observe that occurrence of whistler waves is low, nearly 1.5% and less than 0.5% in the analyzed peak and average BPF data respectively. Whistlers occur highly intermittently and 80% of the whistler… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2101.06723v2-abstract-full').style.display = 'inline'; document.getElementById('2101.06723v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2101.06723v2-abstract-full" style="display: none;"> We studied the properties and occurrence of narrow band whistler waves and their interaction with strahl electrons observed between 0.17 and 0.26 au during the first encounter of Parker Solar Probe. We observe that occurrence of whistler waves is low, nearly 1.5% and less than 0.5% in the analyzed peak and average BPF data respectively. Whistlers occur highly intermittently and 80% of the whistlers appear continuously for less than 3 s. Occurrence rate of whistler waves was found to be anti-correlated with the solar wind bulk velocity. The study of the duration of the whistler intervals revealed an anti-correlation between the duration and the solar wind velocity, as well as between the duration and the normalized amplitude of magnetic field variations. The pitch-angle widths (PAWs) of the field-aligned electron population referred to as the strahl are broader by at least 12 degrees during the presence of large amplitude narrow band whistler waves. This observation points towards a EM wave electron interaction, resulting in pitch-angle scattering. PAW of strahl electrons corresponding to the short duration whistlers are higher compared to the long duration whistlers. Parallel cuts through the strahl electron velocity distribution function (VDF) observed during the whistler intervals appear to depart from the Maxwellian shape typically found in the near-Sun strahl VDFs (Bercic et al. 2020). The relative decrease of parallel electron temperature and the increase of PAW for the electrons in strahl energy range suggests that the interaction with whistler waves results in a transfer of electron momentum from the parallel to the perpendicular direction. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2101.06723v2-abstract-full').style.display = 'none'; document.getElementById('2101.06723v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 31 January, 2021; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 17 January, 2021; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> January 2021. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">Accepted for publication in Astronomy & Astrophysics PSP special issue on January 12, 2021</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> A&A 650, A9 (2021) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2101.06279">arXiv:2101.06279</a> <span> [<a href="https://arxiv.org/pdf/2101.06279">pdf</a>, <a href="https://arxiv.org/ps/2101.06279">ps</a>, <a href="https://arxiv.org/format/2101.06279">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Solar and Stellar Astrophysics">astro-ph.SR</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Space Physics">physics.space-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1051/0004-6361/202039806">10.1051/0004-6361/202039806 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Direct evidence for magnetic reconnection at the boundaries of magnetic switchbacks with Parker Solar Probe </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Froment%2C+C">C. Froment</a>, <a href="/search/physics?searchtype=author&query=Krasnoselskikh%2C+V">V. Krasnoselskikh</a>, <a href="/search/physics?searchtype=author&query=de+Wit%2C+T+D">T. Dudok de Wit</a>, <a href="/search/physics?searchtype=author&query=Agapitov%2C+O">O. Agapitov</a>, <a href="/search/physics?searchtype=author&query=Fargette%2C+N">N. Fargette</a>, <a href="/search/physics?searchtype=author&query=Lavraud%2C+B">B. Lavraud</a>, <a href="/search/physics?searchtype=author&query=Larosa%2C+A">A. Larosa</a>, <a href="/search/physics?searchtype=author&query=Kretzschmar%2C+M">M. Kretzschmar</a>, <a href="/search/physics?searchtype=author&query=Jagarlamudi%2C+V+K">V. K. Jagarlamudi</a>, <a href="/search/physics?searchtype=author&query=Velli%2C+M">M. Velli</a>, <a href="/search/physics?searchtype=author&query=Malaspina%2C+D">D. Malaspina</a>, <a href="/search/physics?searchtype=author&query=Whittlesey%2C+P+L">P. L. Whittlesey</a>, <a href="/search/physics?searchtype=author&query=Bale%2C+S+D">S. D. Bale</a>, <a href="/search/physics?searchtype=author&query=Case%2C+A+W">A. W. Case</a>, <a href="/search/physics?searchtype=author&query=Goetz%2C+K">K. Goetz</a>, <a href="/search/physics?searchtype=author&query=Kasper%2C+J+C">J. C. Kasper</a>, <a href="/search/physics?searchtype=author&query=Korreck%2C+K+E">K. E. Korreck</a>, <a href="/search/physics?searchtype=author&query=Larson%2C+D+E">D. E. Larson</a>, <a href="/search/physics?searchtype=author&query=MacDowall%2C+R+J">R. J. MacDowall</a>, <a href="/search/physics?searchtype=author&query=Mozer%2C+F+S">F. S. Mozer</a>, <a href="/search/physics?searchtype=author&query=Pulupa%2C+M">M. Pulupa</a>, <a href="/search/physics?searchtype=author&query=Revillet%2C+C">C. Revillet</a>, <a href="/search/physics?searchtype=author&query=Stevens%2C+M+L">M. L. Stevens</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2101.06279v2-abstract-short" style="display: inline;"> Parker Solar Probe's first encounters with the Sun revealed the presence of ubiquitous localised magnetic deflections in the inner heliosphere; these structures, often called switchbacks, are particularly striking in solar wind streams originating from coronal holes. We report the direct evidence for magnetic reconnection occuring at the boundaries of three switchbacks crossed by Parker Solar Prob… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2101.06279v2-abstract-full').style.display = 'inline'; document.getElementById('2101.06279v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2101.06279v2-abstract-full" style="display: none;"> Parker Solar Probe's first encounters with the Sun revealed the presence of ubiquitous localised magnetic deflections in the inner heliosphere; these structures, often called switchbacks, are particularly striking in solar wind streams originating from coronal holes. We report the direct evidence for magnetic reconnection occuring at the boundaries of three switchbacks crossed by Parker Solar Probe (PSP) at a distance of 45 to 48 solar radii of the Sun during its first encounter. We analyse the magnetic field and plasma parameters from the FIELDS and SWEAP instruments. The three structures analysed all show typical signatures of magnetic reconnection. The ion velocity and magnetic field are first correlated and then anti-correlated at the inbound and outbound edges of the bifurcated current sheets with a central ion flow jet. Most of the reconnection events have a strong guide field and moderate magnetic shear but one current sheet shows indications of quasi anti-parallel reconnection in conjunction with a magnetic field magnitude decrease by $90\%$. Given the wealth of intense current sheets observed by PSP, reconnection at switchbacks boundaries appears to be rare. However, as the switchback boundaries accomodate currents one can conjecture that the geometry of these boundaries offers favourable conditions for magnetic reconnection to occur. Such a mechanism would thus contribute in reconfiguring the magnetic field of the switchbacks, affecting the dynamics of the solar wind and eventually contributing to the blending of the structures with the regular wind as they propagate away from the Sun. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2101.06279v2-abstract-full').style.display = 'none'; document.getElementById('2101.06279v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 3 March, 2021; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 15 January, 2021; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> January 2021. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">11 pages, 7 figures, 2 tables, accepted for publication in A&A, PSP special issue (v2: typos correction)</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> A&A 650, A5 (2021) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2101.03121">arXiv:2101.03121</a> <span> [<a href="https://arxiv.org/pdf/2101.03121">pdf</a>, <a href="https://arxiv.org/format/2101.03121">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Solar and Stellar Astrophysics">astro-ph.SR</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Space Physics">physics.space-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1051/0004-6361/202039615">10.1051/0004-6361/202039615 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Solar wind energy flux observations in the inner heliosphere: First results from Parker Solar Probe </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Liu%2C+M">M. Liu</a>, <a href="/search/physics?searchtype=author&query=Issautier%2C+K">K. Issautier</a>, <a href="/search/physics?searchtype=author&query=Meyer-Vernet%2C+N">N. Meyer-Vernet</a>, <a href="/search/physics?searchtype=author&query=Moncuquet%2C+M">M. Moncuquet</a>, <a href="/search/physics?searchtype=author&query=Maksimovic%2C+M">M. Maksimovic</a>, <a href="/search/physics?searchtype=author&query=Halekas%2C+J+S">J. S. Halekas</a>, <a href="/search/physics?searchtype=author&query=Huang%2C+J">J. Huang</a>, <a href="/search/physics?searchtype=author&query=Griton%2C+L">L. Griton</a>, <a href="/search/physics?searchtype=author&query=Bale%2C+S">S. Bale</a>, <a href="/search/physics?searchtype=author&query=Bonnell%2C+J+W">J. W. Bonnell</a>, <a href="/search/physics?searchtype=author&query=Case%2C+A+W">A. W. Case</a>, <a href="/search/physics?searchtype=author&query=Goetz%2C+K">K. Goetz</a>, <a href="/search/physics?searchtype=author&query=Harvey%2C+P+R">P. R. Harvey</a>, <a href="/search/physics?searchtype=author&query=Kasper%2C+J+C">J. C. Kasper</a>, <a href="/search/physics?searchtype=author&query=MacDowall%2C+R+J">R. J. MacDowall</a>, <a href="/search/physics?searchtype=author&query=Malaspina%2C+D+M">D. M. Malaspina</a>, <a href="/search/physics?searchtype=author&query=Pulupa%2C+M">M. Pulupa</a>, <a href="/search/physics?searchtype=author&query=Stevens%2C+M+L">M. L. Stevens</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2101.03121v1-abstract-short" style="display: inline;"> We investigate the solar wind energy flux in the inner heliosphere using 12-day observations around each perihelion of Encounter One (E01), Two (E02), Four (E04), and Five (E05) of Parker Solar Probe (PSP), respectively, with a minimum heliocentric distance of 27.8 solar radii ($R_\odot{}$). Energy flux was calculated based on electron parameters (density $n_e$, core electron temperature $T_{c}$,… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2101.03121v1-abstract-full').style.display = 'inline'; document.getElementById('2101.03121v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2101.03121v1-abstract-full" style="display: none;"> We investigate the solar wind energy flux in the inner heliosphere using 12-day observations around each perihelion of Encounter One (E01), Two (E02), Four (E04), and Five (E05) of Parker Solar Probe (PSP), respectively, with a minimum heliocentric distance of 27.8 solar radii ($R_\odot{}$). Energy flux was calculated based on electron parameters (density $n_e$, core electron temperature $T_{c}$, and suprathermal electron temperature $T_{h}$) obtained from the simplified analysis of the plasma quasi-thermal noise (QTN) spectrum measured by RFS/FIELDS and the bulk proton parameters (bulk speed $V_p$ and temperature $T_p$) measured by the Faraday Cup onboard PSP, SPC/SWEAP. Combining observations from E01, E02, E04, and E05, the averaged energy flux value normalized to 1 $R_\odot{}$ plus the energy necessary to overcome the solar gravitation ($W_{R_\odot{}}$) is about 70$\pm$14 $W m^{-2}$, which is similar to the average value (79$\pm$18 $W m^{-2}$) derived by Le Chat et al from 24-year observations by Helios, Ulysses, and Wind at various distances and heliolatitudes. It is remarkable that the distributions of $W_{R_\odot{}}$ are nearly symmetrical and well fitted by Gaussians, much more so than at 1 AU, which may imply that the small heliocentric distance limits the interactions with transient plasma structures. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2101.03121v1-abstract-full').style.display = 'none'; document.getElementById('2101.03121v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 8 January, 2021; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> January 2021. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">8 pages, 6 figures and Astronomy & Astrophysics Accepted</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> A&A 650, A14 (2021) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2101.00830">arXiv:2101.00830</a> <span> [<a href="https://arxiv.org/pdf/2101.00830">pdf</a>, <a href="https://arxiv.org/format/2101.00830">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Solar and Stellar Astrophysics">astro-ph.SR</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Space Physics">physics.space-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1051/0004-6361/202039818">10.1051/0004-6361/202039818 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Alfv茅nic versus non-Alfv茅nic turbulence in the inner heliosphere as observed by Parker Solar Probe </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Shi%2C+C">Chen Shi</a>, <a href="/search/physics?searchtype=author&query=Velli%2C+M">Marco Velli</a>, <a href="/search/physics?searchtype=author&query=Panasenco%2C+O">Olga Panasenco</a>, <a href="/search/physics?searchtype=author&query=Tenerani%2C+A">Anna Tenerani</a>, <a href="/search/physics?searchtype=author&query=R%C3%A9ville%2C+V">Victor R茅ville</a>, <a href="/search/physics?searchtype=author&query=Bale%2C+S+D">Stuart D. Bale</a>, <a href="/search/physics?searchtype=author&query=Kasper%2C+J">Justin Kasper</a>, <a href="/search/physics?searchtype=author&query=Korreck%2C+K">Kelly Korreck</a>, <a href="/search/physics?searchtype=author&query=Bonnell%2C+J+W">J. W. Bonnell</a>, <a href="/search/physics?searchtype=author&query=de+Wit%2C+T+D">Thierry Dudok de Wit</a>, <a href="/search/physics?searchtype=author&query=Malaspina%2C+D+M">David M. Malaspina</a>, <a href="/search/physics?searchtype=author&query=Goetz%2C+K">Keith Goetz</a>, <a href="/search/physics?searchtype=author&query=Harvey%2C+P+R">Peter R. Harvey</a>, <a href="/search/physics?searchtype=author&query=MacDowall%2C+R+J">Robert J. MacDowall</a>, <a href="/search/physics?searchtype=author&query=Pulupa%2C+M">Marc Pulupa</a>, <a href="/search/physics?searchtype=author&query=Case%2C+A+W">Anthony W. Case</a>, <a href="/search/physics?searchtype=author&query=Larson%2C+D">Davin Larson</a>, <a href="/search/physics?searchtype=author&query=Verniero%2C+J+L">J. L. Verniero</a>, <a href="/search/physics?searchtype=author&query=Livi%2C+R">Roberto Livi</a>, <a href="/search/physics?searchtype=author&query=Stevens%2C+M">Michael Stevens</a>, <a href="/search/physics?searchtype=author&query=Whittlesey%2C+P">Phyllis Whittlesey</a>, <a href="/search/physics?searchtype=author&query=Maksimovic%2C+M">Milan Maksimovic</a>, <a href="/search/physics?searchtype=author&query=Moncuquet%2C+M">Michel Moncuquet</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2101.00830v2-abstract-short" style="display: inline;"> We make use of the Parker Solar Probe (PSP) data to explore the nature of solar wind turbulence focusing on the Alfv茅nic character and power spectra of the fluctuations and their dependence on distance and context (i.e. large scale solar wind properties), aiming to understand the role that different effects such as source properties, solar wind expansion, stream interaction might play in determini… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2101.00830v2-abstract-full').style.display = 'inline'; document.getElementById('2101.00830v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2101.00830v2-abstract-full" style="display: none;"> We make use of the Parker Solar Probe (PSP) data to explore the nature of solar wind turbulence focusing on the Alfv茅nic character and power spectra of the fluctuations and their dependence on distance and context (i.e. large scale solar wind properties), aiming to understand the role that different effects such as source properties, solar wind expansion, stream interaction might play in determining the turbulent state. We carry out a statistical survey of the data from the first five orbits of PSP with a focus on how the fluctuation properties at the large, MHD scales, vary with different solar wind streams and distance from the Sun. A more in-depth analysis from several selected periods is also presented. Our results show that as fluctuations are transported outward by the solar wind, the magnetic field spectrum steepens while the shape of the velocity spectrum remains unchanged. The steepening process is controlled by the "age" of the turbulence, determined by the wind speed together with the radial distance. Statistically, faster solar wind has higher "Alfv茅nicity", with more dominant outward propagating wave component and more balanced magnetic/kinetic energies. The outward wave dominance gradually weakens with radial distance, while the excess of magnetic energy is found to be stronger as we move closer toward the Sun. We show that the turbulence properties can vary significantly stream to stream even if these streams are of similar speed, indicating very different origins of these streams. Especially, the slow wind that originates near the polar coronal holes has much lower Alfv茅nicity compared with the slow wind that originates from the active regions/pseudostreamers. We show that structures such as heliospheric current sheets and velocity shears can play an important role in modifying the properties of the turbulence. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2101.00830v2-abstract-full').style.display = 'none'; document.getElementById('2101.00830v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 27 January, 2021; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 4 January, 2021; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> January 2021. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> A&A 650, A21 (2021) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2012.10420">arXiv:2012.10420</a> <span> [<a href="https://arxiv.org/pdf/2012.10420">pdf</a>, <a href="https://arxiv.org/format/2012.10420">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Solar and Stellar Astrophysics">astro-ph.SR</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Space Physics">physics.space-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1051/0004-6361/202039442">10.1051/0004-6361/202039442 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Switchbacks: statistical properties and deviations from alfv茅nicity </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Larosa%2C+A">A. Larosa</a>, <a href="/search/physics?searchtype=author&query=Krasnoselskikh%2C+V">V. Krasnoselskikh</a>, <a href="/search/physics?searchtype=author&query=de+Wit%C4%B1nst%2C+T+D">T. Dudok de Wit谋nst</a>, <a href="/search/physics?searchtype=author&query=Agapitov%2C+O">O. Agapitov</a>, <a href="/search/physics?searchtype=author&query=Froment%2C+C">C. Froment</a>, <a href="/search/physics?searchtype=author&query=Jagarlamudi%2C+V+K">V. K. Jagarlamudi</a>, <a href="/search/physics?searchtype=author&query=Velli%2C+M">M. Velli</a>, <a href="/search/physics?searchtype=author&query=Bale%2C+S+D">S. D. Bale</a>, <a href="/search/physics?searchtype=author&query=Case%2C+A+W">A. W. Case</a>, <a href="/search/physics?searchtype=author&query=Goetz%2C+K">K. Goetz</a>, <a href="/search/physics?searchtype=author&query=Harvey%2C+K+P">Keith P. Harvey</a>, <a href="/search/physics?searchtype=author&query=Kasper%2C+J+C">J. C. Kasper</a>, <a href="/search/physics?searchtype=author&query=Korreck%2C+K+E">K. E. Korreck</a>, <a href="/search/physics?searchtype=author&query=Larson%2C+D+E">D. E. Larson</a>, <a href="/search/physics?searchtype=author&query=MacDowall%2C+R+J">R. J. MacDowall</a>, <a href="/search/physics?searchtype=author&query=Malaspina%2C+D">D. Malaspina</a>, <a href="/search/physics?searchtype=author&query=Pulupa%2C+M">M. Pulupa</a>, <a href="/search/physics?searchtype=author&query=Revillet%2C+C">C. Revillet</a>, <a href="/search/physics?searchtype=author&query=Stevens%2C+M+L">M. L. Stevens</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2012.10420v1-abstract-short" style="display: inline;"> {Parker Solar Probe's first solar encounter has revealed the presence of sudden magnetic field deflections that are called switchbacks and are associated with proton velocity enhancements in the slow alfv茅nic solar wind.} {We study their statistical properties with a special focus on their boundaries.} {Using data from SWEAP and FIELDS we investigate particle and wavefield properties. The magnetic… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2012.10420v1-abstract-full').style.display = 'inline'; document.getElementById('2012.10420v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2012.10420v1-abstract-full" style="display: none;"> {Parker Solar Probe's first solar encounter has revealed the presence of sudden magnetic field deflections that are called switchbacks and are associated with proton velocity enhancements in the slow alfv茅nic solar wind.} {We study their statistical properties with a special focus on their boundaries.} {Using data from SWEAP and FIELDS we investigate particle and wavefield properties. The magnetic boundaries are analyzed with the minimum variance technique.} {Switchbacks are found to be alfv茅nic in 73\% of the cases and compressible in 27\%. The correlations between magnetic field magnitude and density fluctuations reveal the existence of both positive and negative correlations, and the absence of perturbations of the magnetic field magnitude. Switchbacks do not lead to a magnetic shear in the ambient field. Their boundaries can be interpreted in terms of rotational or tangential discontinuities. The former are more frequent.} {Our findings provide constraints on the possible generation mechanisms of switchbacks, which has to be able to account also for structures that are not purely alfv茅nic. One of the possible candidates, among others, manifesting the described characteristics is the firehose instability.} <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2012.10420v1-abstract-full').style.display = 'none'; document.getElementById('2012.10420v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 18 December, 2020; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> December 2020. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> A&A 650, A3 (2021) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2010.15189">arXiv:2010.15189</a> <span> [<a href="https://arxiv.org/pdf/2010.15189">pdf</a>, <a href="https://arxiv.org/format/2010.15189">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Space Physics">physics.space-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Plasma Physics">physics.plasm-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1051/0004-6361/202039296">10.1051/0004-6361/202039296 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Wave-particle energy transfer directly observed in an ion cyclotron wave </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Vech%2C+D">Daniel Vech</a>, <a href="/search/physics?searchtype=author&query=Martinovic%2C+M+M">Mihailo M. Martinovic</a>, <a href="/search/physics?searchtype=author&query=Klein%2C+K+G">Kristopher G. Klein</a>, <a href="/search/physics?searchtype=author&query=Malaspina%2C+D+M">David M. Malaspina</a>, <a href="/search/physics?searchtype=author&query=Bowen%2C+T+A">Trevor A. Bowen</a>, <a href="/search/physics?searchtype=author&query=Verniero%2C+J+L">Jenny L. Verniero</a>, <a href="/search/physics?searchtype=author&query=Paulson%2C+K">Kristoff Paulson</a>, <a href="/search/physics?searchtype=author&query=de+Wit%2C+T+D">Thierry Dudok de Wit</a>, <a href="/search/physics?searchtype=author&query=Kasper%2C+J+C">Justin C. Kasper</a>, <a href="/search/physics?searchtype=author&query=Huang%2C+J">Jia Huang</a>, <a href="/search/physics?searchtype=author&query=Stevens%2C+M+L">Michael L. Stevens</a>, <a href="/search/physics?searchtype=author&query=Case%2C+A+W">Anthony W. Case</a>, <a href="/search/physics?searchtype=author&query=Korreck%2C+K">Kelly Korreck</a>, <a href="/search/physics?searchtype=author&query=Mozer%2C+F+S">Forrest S. Mozer</a>, <a href="/search/physics?searchtype=author&query=Goodrich%2C+K+A">Katherine A. Goodrich</a>, <a href="/search/physics?searchtype=author&query=Bale%2C+S+D">Stuart D. Bale</a>, <a href="/search/physics?searchtype=author&query=Whittlesey%2C+P+L">Phyllis L. Whittlesey</a>, <a href="/search/physics?searchtype=author&query=Livi%2C+R">Roberto Livi</a>, <a href="/search/physics?searchtype=author&query=Larson%2C+D+E">Davin E. Larson</a>, <a href="/search/physics?searchtype=author&query=Pulupa%2C+M">Marc Pulupa</a>, <a href="/search/physics?searchtype=author&query=Bonnell%2C+J">John Bonnell</a>, <a href="/search/physics?searchtype=author&query=Harvey%2C+P">Peter Harvey</a>, <a href="/search/physics?searchtype=author&query=Goetz%2C+K">Keith Goetz</a>, <a href="/search/physics?searchtype=author&query=MacDowall%2C+R">Robert MacDowall</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2010.15189v1-abstract-short" style="display: inline;"> Context. The first studies with Parker Solar Probe (PSP) data have made significant progress toward the understanding of the fundamental properties of ion cyclotron waves in the inner heliosphere. The survey mode particle measurements of PSP, however, did not make it possible to measure the coupling between electromagnetic fields and particles on the time scale of the wave periods. Aims. We pres… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2010.15189v1-abstract-full').style.display = 'inline'; document.getElementById('2010.15189v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2010.15189v1-abstract-full" style="display: none;"> Context. The first studies with Parker Solar Probe (PSP) data have made significant progress toward the understanding of the fundamental properties of ion cyclotron waves in the inner heliosphere. The survey mode particle measurements of PSP, however, did not make it possible to measure the coupling between electromagnetic fields and particles on the time scale of the wave periods. Aims. We present a novel approach to study wave-particle energy exchange with PSP. Methods. We use the Flux Angle operation mode of the Solar Probe Cup in conjunction with the electric field measurements and present a case study when the Flux Angle mode measured the direct interaction of the proton velocity distribution with an ion cyclotron wave. Results. Our results suggest that the energy transfer from fields to particles on the timescale of a cyclotron period is equal to approximately 3-6% of the electromagnetic energy flux. This rate is consistent with the hypothesis that the ion cyclotron wave was locally generated in the solar wind. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2010.15189v1-abstract-full').style.display = 'none'; document.getElementById('2010.15189v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 28 October, 2020; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> October 2020. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">Accepted in Astronomy and Astrophysics</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2010.10302">arXiv:2010.10302</a> <span> [<a href="https://arxiv.org/pdf/2010.10302">pdf</a>, <a href="https://arxiv.org/ps/2010.10302">ps</a>, <a href="https://arxiv.org/format/2010.10302">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Solar and Stellar Astrophysics">astro-ph.SR</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Plasma Physics">physics.plasm-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Space Physics">physics.space-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1051/0004-6361/202039256">10.1051/0004-6361/202039256 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Electron heat flux in the near-Sun environment </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Halekas%2C+J+S">J. S. Halekas</a>, <a href="/search/physics?searchtype=author&query=Whittlesey%2C+P+L">P. L. Whittlesey</a>, <a href="/search/physics?searchtype=author&query=Larson%2C+D+E">D. E. Larson</a>, <a href="/search/physics?searchtype=author&query=McGinnis%2C+D">D. McGinnis</a>, <a href="/search/physics?searchtype=author&query=Bale%2C+S+D">S. D. Bale</a>, <a href="/search/physics?searchtype=author&query=Berthomier%2C+M">M. Berthomier</a>, <a href="/search/physics?searchtype=author&query=Case%2C+A+W">A. W. Case</a>, <a href="/search/physics?searchtype=author&query=Chandran%2C+B+D+G">B. D. G. Chandran</a>, <a href="/search/physics?searchtype=author&query=Kasper%2C+J+C">J. C. Kasper</a>, <a href="/search/physics?searchtype=author&query=Klein%2C+K+G">K. G. Klein</a>, <a href="/search/physics?searchtype=author&query=Korreck%2C+K+E">K. E. Korreck</a>, <a href="/search/physics?searchtype=author&query=Livi%2C+R">R. Livi</a>, <a href="/search/physics?searchtype=author&query=MacDowall%2C+R+J">R. J. MacDowall</a>, <a href="/search/physics?searchtype=author&query=Maksimovic%2C+M">M. Maksimovic</a>, <a href="/search/physics?searchtype=author&query=Malaspina%2C+D+M">D. M. Malaspina</a>, <a href="/search/physics?searchtype=author&query=Matteini%2C+L">L. Matteini</a>, <a href="/search/physics?searchtype=author&query=Pulupa%2C+M+P">M. P. Pulupa</a>, <a href="/search/physics?searchtype=author&query=Stevens%2C+M+L">M. L. Stevens</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2010.10302v1-abstract-short" style="display: inline;"> We survey the electron heat flux observed by the Parker Solar Probe (PSP) in the near-Sun environment at heliocentric distances of 0.125-0.25 AU. We utilized measurements from the Solar Wind Electrons Alphas and Protons and FIELDS experiments to compute the solar wind electron heat flux and its components and to place these in context. The PSP observations reveal a number of trends in the electron… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2010.10302v1-abstract-full').style.display = 'inline'; document.getElementById('2010.10302v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2010.10302v1-abstract-full" style="display: none;"> We survey the electron heat flux observed by the Parker Solar Probe (PSP) in the near-Sun environment at heliocentric distances of 0.125-0.25 AU. We utilized measurements from the Solar Wind Electrons Alphas and Protons and FIELDS experiments to compute the solar wind electron heat flux and its components and to place these in context. The PSP observations reveal a number of trends in the electron heat flux signatures near the Sun. The magnitude of the heat flux is anticorrelated with solar wind speed, likely as a result of the lower saturation heat flux in the higher-speed wind. When divided by the saturation heat flux, the resulting normalized net heat flux is anticorrelated with plasma beta on all PSP orbits, which is consistent with the operation of collisionless heat flux regulation mechanisms. The net heat flux also decreases in very high beta regions in the vicinity of the heliospheric current sheet, but in most cases of this type the omnidirectional suprathermal electron flux remains at a comparable level or even increases, seemingly inconsistent with disconnection from the Sun. The measured heat flux values appear inconsistent with regulation primarily by collisional mechanisms near the Sun. Instead, the observed heat flux dependence on plasma beta and the distribution of suprathermal electron parameters are both consistent with theoretical instability thresholds associated with oblique whistler and magnetosonic modes. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2010.10302v1-abstract-full').style.display = 'none'; document.getElementById('2010.10302v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 20 October, 2020; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> October 2020. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> A&A 650, A15 (2021) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2010.10211">arXiv:2010.10211</a> <span> [<a href="https://arxiv.org/pdf/2010.10211">pdf</a>, <a href="https://arxiv.org/format/2010.10211">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Space Physics">physics.space-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Solar and Stellar Astrophysics">astro-ph.SR</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Plasma Physics">physics.plasm-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1051/0004-6361/202039354">10.1051/0004-6361/202039354 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Statistical analysis of orientation, shape, and size of solar wind switchbacks </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Laker%2C+R">Ronan Laker</a>, <a href="/search/physics?searchtype=author&query=Horbury%2C+T+S">Timothy S. Horbury</a>, <a href="/search/physics?searchtype=author&query=Bale%2C+S+D">Stuart D. Bale</a>, <a href="/search/physics?searchtype=author&query=Matteini%2C+L">Lorenzo Matteini</a>, <a href="/search/physics?searchtype=author&query=Woolley%2C+T">Thomas Woolley</a>, <a href="/search/physics?searchtype=author&query=Woodham%2C+L+D">Lloyd D. Woodham</a>, <a href="/search/physics?searchtype=author&query=Badman%2C+S+T">Samuel T. Badman</a>, <a href="/search/physics?searchtype=author&query=Pulupa%2C+M">Marc Pulupa</a>, <a href="/search/physics?searchtype=author&query=Kasper%2C+J+C">Justin C. Kasper</a>, <a href="/search/physics?searchtype=author&query=Stevens%2C+M">Michael Stevens</a>, <a href="/search/physics?searchtype=author&query=Case%2C+A+W">Anthony W. Case</a>, <a href="/search/physics?searchtype=author&query=Korreck%2C+K+E">Kelly E. Korreck</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2010.10211v1-abstract-short" style="display: inline;"> One of the main discoveries from the first two orbits of Parker Solar Probe (PSP) was the presence of magnetic switchbacks, whose deflections dominated the magnetic field measurements. Determining their shape and size could provide evidence of their origin, which is still unclear. Previous work with a single solar wind stream has indicated that these are long, thin structures although the directio… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2010.10211v1-abstract-full').style.display = 'inline'; document.getElementById('2010.10211v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2010.10211v1-abstract-full" style="display: none;"> One of the main discoveries from the first two orbits of Parker Solar Probe (PSP) was the presence of magnetic switchbacks, whose deflections dominated the magnetic field measurements. Determining their shape and size could provide evidence of their origin, which is still unclear. Previous work with a single solar wind stream has indicated that these are long, thin structures although the direction of their major axis could not be determined. We investigate if this long, thin nature extends to other solar wind streams, while determining the direction along which the switchbacks within a stream were aligned. We try to understand how the size and orientation of the switchbacks, along with the flow velocity and spacecraft trajectory, combine to produce the observed structure durations for past and future orbits. We searched for the alignment direction that produced a combination of a spacecraft cutting direction and switchback duration that was most consistent with long, thin structures. The expected form of a long, thin structure was fitted to the results of the best alignment direction, which determined the width and aspect ratio of the switchbacks for that stream. The switchbacks had a mean width of $50,000 \, \rm{km}$, with an aspect ratio of the order of $10$. We find that switchbacks are not aligned along the background flow direction, but instead aligned along the local Parker spiral, perhaps suggesting that they propagate along the magnetic field. Since the observed switchback duration depends on how the spacecraft cuts through the structure, the duration alone cannot be used to determine the size or influence of an individual event. For future PSP orbits, a larger spacecraft transverse component combined with more radially aligned switchbacks will lead to long duration switchbacks becoming less common. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2010.10211v1-abstract-full').style.display = 'none'; document.getElementById('2010.10211v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 20 October, 2020; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> October 2020. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> A&A 650, A1 (2021) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2010.04664">arXiv:2010.04664</a> <span> [<a href="https://arxiv.org/pdf/2010.04664">pdf</a>, <a href="https://arxiv.org/format/2010.04664">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Solar and Stellar Astrophysics">astro-ph.SR</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Space Physics">physics.space-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1051/0004-6361/202039298">10.1051/0004-6361/202039298 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Detection of small magnetic flux ropes from the third and fourth Parker Solar Probe encounters </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Zhao%2C+L+-">L. -L. Zhao</a>, <a href="/search/physics?searchtype=author&query=Zank%2C+G+P">G. P. Zank</a>, <a href="/search/physics?searchtype=author&query=Hu%2C+Q">Q. Hu</a>, <a href="/search/physics?searchtype=author&query=Telloni%2C+D">D. Telloni</a>, <a href="/search/physics?searchtype=author&query=Chen%2C+Y">Y. Chen</a>, <a href="/search/physics?searchtype=author&query=Adhikari%2C+L">L. Adhikari</a>, <a href="/search/physics?searchtype=author&query=Nakanotani%2C+M">M. Nakanotani</a>, <a href="/search/physics?searchtype=author&query=Kasper%2C+J+C">J. C. Kasper</a>, <a href="/search/physics?searchtype=author&query=Huang%2C+J">J. Huang</a>, <a href="/search/physics?searchtype=author&query=Bale%2C+S+D">S. D. Bale</a>, <a href="/search/physics?searchtype=author&query=Korreck%2C+K+E">K. E. Korreck</a>, <a href="/search/physics?searchtype=author&query=Case%2C+A+W">A. W. Case</a>, <a href="/search/physics?searchtype=author&query=Stevens%2C+M">M. Stevens</a>, <a href="/search/physics?searchtype=author&query=Bonnell%2C+J+W">J. W. Bonnell</a>, <a href="/search/physics?searchtype=author&query=de+Wit%2C+T+D">T. Dudok de Wit</a>, <a href="/search/physics?searchtype=author&query=Goetz%2C+K">K. Goetz</a>, <a href="/search/physics?searchtype=author&query=Harvey%2C+P+R">P. R. Harvey</a>, <a href="/search/physics?searchtype=author&query=MacDowall%2C+R+J">R. J. MacDowall</a>, <a href="/search/physics?searchtype=author&query=Malaspina%2C+D+M">D. M. Malaspina</a>, <a href="/search/physics?searchtype=author&query=Pulupa%2C+M">M. Pulupa</a>, <a href="/search/physics?searchtype=author&query=Larson%2C+D+E">D. E. Larson</a>, <a href="/search/physics?searchtype=author&query=Livi%2C+R">R. Livi</a>, <a href="/search/physics?searchtype=author&query=Whittlesey%2C+P">P. Whittlesey</a>, <a href="/search/physics?searchtype=author&query=Klein%2C+K+G">K. G. Klein</a>, <a href="/search/physics?searchtype=author&query=Raouafi%2C+N+E">N. E. Raouafi</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2010.04664v1-abstract-short" style="display: inline;"> We systematically search for magnetic flux rope structures in the solar wind to within the closest distance to the Sun of 0.13 AU, using data from the third and fourth orbits of the Parker Solar Probe. We extend our previous magnetic helicity based technique of identifying magnetic flux rope structures. The method is improved upon to incorporate the azimuthal flow, which becomes larger as the spac… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2010.04664v1-abstract-full').style.display = 'inline'; document.getElementById('2010.04664v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2010.04664v1-abstract-full" style="display: none;"> We systematically search for magnetic flux rope structures in the solar wind to within the closest distance to the Sun of 0.13 AU, using data from the third and fourth orbits of the Parker Solar Probe. We extend our previous magnetic helicity based technique of identifying magnetic flux rope structures. The method is improved upon to incorporate the azimuthal flow, which becomes larger as the spacecraft approaches the Sun. A total of 21 and 34 magnetic flux ropes are identified during the third (21 days period) and fourth (17 days period) orbits of the Parker Solar Probe, respectively. We provide a statistical analysis of the identified structures, including their relation to the streamer belt and heliospheric current sheet crossing. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2010.04664v1-abstract-full').style.display = 'none'; document.getElementById('2010.04664v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 9 October, 2020; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> October 2020. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> A&A 650, A12 (2021) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2007.10906">arXiv:2007.10906</a> <span> [<a href="https://arxiv.org/pdf/2007.10906">pdf</a>, <a href="https://arxiv.org/format/2007.10906">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Space Physics">physics.space-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Solar and Stellar Astrophysics">astro-ph.SR</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Plasma Physics">physics.plasm-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1093/mnras/staa2770">10.1093/mnras/staa2770 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Proton Core Behaviour Inside Magnetic Field Switchbacks </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Woolley%2C+T">Thomas Woolley</a>, <a href="/search/physics?searchtype=author&query=Matteini%2C+L">Lorenzo Matteini</a>, <a href="/search/physics?searchtype=author&query=Horbury%2C+T+S">Timothy S. Horbury</a>, <a href="/search/physics?searchtype=author&query=Bale%2C+S+D">Stuart D. Bale</a>, <a href="/search/physics?searchtype=author&query=Woodham%2C+L+D">Lloyd D. Woodham</a>, <a href="/search/physics?searchtype=author&query=Laker%2C+R">Ronan Laker</a>, <a href="/search/physics?searchtype=author&query=Alterman%2C+B+L">Benjamin L. Alterman</a>, <a href="/search/physics?searchtype=author&query=Bonnell%2C+J+W">John W. Bonnell</a>, <a href="/search/physics?searchtype=author&query=Case%2C+A+W">Anthony W. Case</a>, <a href="/search/physics?searchtype=author&query=Kasper%2C+J+C">Justin C. Kasper</a>, <a href="/search/physics?searchtype=author&query=Klein%2C+K+G">Kristopher G. Klein</a>, <a href="/search/physics?searchtype=author&query=Martinovi%C4%87%2C+M+M">Mihailo M. Martinovi膰</a>, <a href="/search/physics?searchtype=author&query=Stevens%2C+M">Michael Stevens</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2007.10906v1-abstract-short" style="display: inline;"> During Parker Solar Probe's first two orbits there are widespread observations of rapid magnetic field reversals known as switchbacks. These switchbacks are extensively found in the near-Sun solar wind, appear to occur in patches, and have possible links to various phenomena such as magnetic reconnection near the solar surface. As switchbacks are associated with faster plasma flows, we questioned… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2007.10906v1-abstract-full').style.display = 'inline'; document.getElementById('2007.10906v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2007.10906v1-abstract-full" style="display: none;"> During Parker Solar Probe's first two orbits there are widespread observations of rapid magnetic field reversals known as switchbacks. These switchbacks are extensively found in the near-Sun solar wind, appear to occur in patches, and have possible links to various phenomena such as magnetic reconnection near the solar surface. As switchbacks are associated with faster plasma flows, we questioned whether they are hotter than the background plasma and whether the microphysics inside a switchback is different to its surroundings. We have studied the reduced distribution functions from the Solar Probe Cup instrument and considered time periods with markedly large angular deflections, to compare parallel temperatures inside and outside switchbacks. We have shown that the reduced distribution functions inside switchbacks are consistent with a rigid phase space rotation of the background plasma. As such, we conclude that the proton core parallel temperature is the same inside and outside of switchbacks, implying that a T-V relationship does not hold for the proton core parallel temperature inside magnetic field switchbacks. We further conclude that switchbacks are consistent with Alfv茅nic pulses travelling along open magnetic field lines. The origin of these pulses, however, remains unknown. We also found that there is no obvious link between radial Poynting flux and kinetic energy enhancements suggesting that the radial Poynting flux is not important for the dynamics of switchbacks. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2007.10906v1-abstract-full').style.display = 'none'; document.getElementById('2007.10906v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 21 July, 2020; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> July 2020. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">Submitted to Monthly Notices of the Royal Astronomical Society</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2007.04551">arXiv:2007.04551</a> <span> [<a href="https://arxiv.org/pdf/2007.04551">pdf</a>, <a href="https://arxiv.org/ps/2007.04551">ps</a>, <a href="https://arxiv.org/format/2007.04551">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Space Physics">physics.space-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Solar and Stellar Astrophysics">astro-ph.SR</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.3847/1538-4357/abb820">10.3847/1538-4357/abb820 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Small-scale Magnetic Flux Ropes in the First two Parker Solar Probe Encounters </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Chen%2C+Y">Yu Chen</a>, <a href="/search/physics?searchtype=author&query=Hu%2C+Q">Qiang Hu</a>, <a href="/search/physics?searchtype=author&query=Zhao%2C+L">Lingling Zhao</a>, <a href="/search/physics?searchtype=author&query=Kasper%2C+J+C">Justin C. Kasper</a>, <a href="/search/physics?searchtype=author&query=Bale%2C+S+D">Stuart D. Bale</a>, <a href="/search/physics?searchtype=author&query=Korreck%2C+K+E">Kelly E. Korreck</a>, <a href="/search/physics?searchtype=author&query=Case%2C+A+W">Anthony W. Case</a>, <a href="/search/physics?searchtype=author&query=Stevens%2C+M+L">Michael L. Stevens</a>, <a href="/search/physics?searchtype=author&query=Bonnell%2C+J+W">John W. Bonnell</a>, <a href="/search/physics?searchtype=author&query=Goetz%2C+K">Keith Goetz</a>, <a href="/search/physics?searchtype=author&query=Harvey%2C+P+R">Peter R. Harvey</a>, <a href="/search/physics?searchtype=author&query=Klein%2C+K+G">Kristopher G. Klein</a>, <a href="/search/physics?searchtype=author&query=Larson%2C+D+E">Davin E. Larson</a>, <a href="/search/physics?searchtype=author&query=Livi%2C+R">Roberto Livi</a>, <a href="/search/physics?searchtype=author&query=MacDowall%2C+R+J">Robert J. MacDowall</a>, <a href="/search/physics?searchtype=author&query=Malaspina%2C+D+M">David M. Malaspina</a>, <a href="/search/physics?searchtype=author&query=Pulupa%2C+M">Marc Pulupa</a>, <a href="/search/physics?searchtype=author&query=Whittlesey%2C+P+L">Phyllis L. Whittlesey</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2007.04551v2-abstract-short" style="display: inline;"> Small-scale magnetic flux ropes (SFRs) are a type of structures in the solar wind that possess helical magnetic field lines. In a recent report (Chen & Hu 2020), we presented the radial variations of the properties of SFR from 0.29 to 8 au using in situ measurements from the Helios, ACE/Wind, Ulysses, and Voyager spacecraft. With the launch of the Parker Solar Probe (PSP), we extend our previous i… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2007.04551v2-abstract-full').style.display = 'inline'; document.getElementById('2007.04551v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2007.04551v2-abstract-full" style="display: none;"> Small-scale magnetic flux ropes (SFRs) are a type of structures in the solar wind that possess helical magnetic field lines. In a recent report (Chen & Hu 2020), we presented the radial variations of the properties of SFR from 0.29 to 8 au using in situ measurements from the Helios, ACE/Wind, Ulysses, and Voyager spacecraft. With the launch of the Parker Solar Probe (PSP), we extend our previous investigation further into the inner heliosphere. We apply a Grad-Shafranov-based algorithm to identify SFRs during the first two PSP encounters. We find that the number of SFRs detected near the Sun is much less than that at larger radial distances, where magnetohydrodynamic (MHD) turbulence may act as the local source to produce these structures. The prevalence of Alfvenic structures significantly suppresses the detection of SFRs at closer distances. We compare the SFR event list with other event identification methods, yielding a dozen well-matched events. The cross-section maps of two selected events confirm the cylindrical magnetic flux rope configuration. The power-law relation between the SFR magnetic field and heliocentric distances seems to hold down to 0.16 au. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2007.04551v2-abstract-full').style.display = 'none'; document.getElementById('2007.04551v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 13 September, 2020; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 9 July, 2020; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> July 2020. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">Accepted by ApJ on 2020 Sep 10</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2006.00776">arXiv:2006.00776</a> <span> [<a href="https://arxiv.org/pdf/2006.00776">pdf</a>, <a href="https://arxiv.org/format/2006.00776">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Space Physics">physics.space-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Earth and Planetary Astrophysics">astro-ph.EP</span> </div> </div> <p class="title is-5 mathjax"> Dust impact voltage signatures on Parker Solar Probe: influence of spacecraft floating potential </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Bale%2C+S+D">S. D. Bale</a>, <a href="/search/physics?searchtype=author&query=Goetz%2C+K">K. Goetz</a>, <a href="/search/physics?searchtype=author&query=Bonnell%2C+J+W">J. W. Bonnell</a>, <a href="/search/physics?searchtype=author&query=Case%2C+A+W">A. W. Case</a>, <a href="/search/physics?searchtype=author&query=Chen%2C+C+H+K">C. H. K. Chen</a>, <a href="/search/physics?searchtype=author&query=de+Wit%2C+T+D">T. Dudok de Wit</a>, <a href="/search/physics?searchtype=author&query=Gasque%2C+L+C">L. C. Gasque</a>, <a href="/search/physics?searchtype=author&query=Harvey%2C+P+R">P. R. Harvey</a>, <a href="/search/physics?searchtype=author&query=Kasper%2C+J+C">J. C. Kasper</a>, <a href="/search/physics?searchtype=author&query=Kellogg%2C+P+J">P. J. Kellogg</a>, <a href="/search/physics?searchtype=author&query=MacDowall%2C+R+J">R. J. MacDowall</a>, <a href="/search/physics?searchtype=author&query=Maksimovic%2C+M">M. Maksimovic</a>, <a href="/search/physics?searchtype=author&query=Malaspina%2C+D+M">D. M. Malaspina</a>, <a href="/search/physics?searchtype=author&query=Page%2C+B+F">B. F. Page</a>, <a href="/search/physics?searchtype=author&query=Pulupa%2C+M">M. Pulupa</a>, <a href="/search/physics?searchtype=author&query=Stevens%2C+M+L">M. L. Stevens</a>, <a href="/search/physics?searchtype=author&query=Szalay%2C+J+R">J. R. Szalay</a>, <a href="/search/physics?searchtype=author&query=Zaslavsky%2C+A">A. Zaslavsky</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2006.00776v1-abstract-short" style="display: inline;"> When a fast dust particle hits a spacecraft, it generates a cloud of plasma some of which escapes into space and the momentary charge imbalance perturbs the spacecraft voltage with respect to the plasma. Electrons race ahead of ions, however both respond to the DC electric field of the spacecraft. If the spacecraft potential is positive with respect to the plasma, it should attract the dust cloud… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2006.00776v1-abstract-full').style.display = 'inline'; document.getElementById('2006.00776v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2006.00776v1-abstract-full" style="display: none;"> When a fast dust particle hits a spacecraft, it generates a cloud of plasma some of which escapes into space and the momentary charge imbalance perturbs the spacecraft voltage with respect to the plasma. Electrons race ahead of ions, however both respond to the DC electric field of the spacecraft. If the spacecraft potential is positive with respect to the plasma, it should attract the dust cloud electrons and repel the ions, and vice versa. Here we use measurements of impulsive voltage signals from dust impacts on the Parker Solar Probe (PSP) spacecraft to show that the peak voltage amplitude is clearly related to the spacecraft floating potential, consistent with theoretical models and laboratory measurements. In addition, we examine some timescales associated with the voltage waveforms and compare to the timescales of spacecraft charging physics. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2006.00776v1-abstract-full').style.display = 'none'; document.getElementById('2006.00776v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 1 June, 2020; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> June 2020. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">12 pages, 4 figures, 1 table, submitted to Geophysical Research Letters</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2005.12372">arXiv:2005.12372</a> <span> [<a href="https://arxiv.org/pdf/2005.12372">pdf</a>, <a href="https://arxiv.org/format/2005.12372">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Space Physics">physics.space-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Solar and Stellar Astrophysics">astro-ph.SR</span> </div> </div> <p class="title is-5 mathjax"> Alfv茅nic Slow Solar Wind Observed in the Inner Heliosphere by Parker Solar Probe </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Huang%2C+J">Jia Huang</a>, <a href="/search/physics?searchtype=author&query=Kasper%2C+J+C">J. C. Kasper</a>, <a href="/search/physics?searchtype=author&query=Stevens%2C+M">M. Stevens</a>, <a href="/search/physics?searchtype=author&query=Vech%2C+D">D. Vech</a>, <a href="/search/physics?searchtype=author&query=Klein%2C+K+G">K. G. Klein</a>, <a href="/search/physics?searchtype=author&query=Martinovi%C4%87%2C+M+M">Mihailo M. Martinovi膰</a>, <a href="/search/physics?searchtype=author&query=Alterman%2C+B+L">B. L. Alterman</a>, <a href="/search/physics?searchtype=author&query=Jian%2C+L+K">Lan K. Jian</a>, <a href="/search/physics?searchtype=author&query=Hu%2C+Q">Qiang Hu</a>, <a href="/search/physics?searchtype=author&query=Velli%2C+M">Marco Velli</a>, <a href="/search/physics?searchtype=author&query=Horbury%2C+T+S">Timothy S. Horbury</a>, <a href="/search/physics?searchtype=author&query=Lavraud%2C+B">B. Lavraud</a>, <a href="/search/physics?searchtype=author&query=Parashar%2C+T+N">T. N. Parashar</a>, <a href="/search/physics?searchtype=author&query=%C4%8Eurovcov%C3%A1%2C+T">Tereza 膸urovcov谩</a>, <a href="/search/physics?searchtype=author&query=Niembro%2C+T">Tatiana Niembro</a>, <a href="/search/physics?searchtype=author&query=Paulson%2C+K">Kristoff Paulson</a>, <a href="/search/physics?searchtype=author&query=Hegedus%2C+A">A. Hegedus</a>, <a href="/search/physics?searchtype=author&query=Bert%2C+C+M">C. M. Bert</a>, <a href="/search/physics?searchtype=author&query=Holmes%2C+J">J. Holmes</a>, <a href="/search/physics?searchtype=author&query=Case%2C+A+W">A. W. Case</a>, <a href="/search/physics?searchtype=author&query=Korreck%2C+K+E">K. E. Korreck</a>, <a href="/search/physics?searchtype=author&query=Bale%2C+S+D">Stuart D. Bale</a>, <a href="/search/physics?searchtype=author&query=Larson%2C+D+E">Davin E. Larson</a>, <a href="/search/physics?searchtype=author&query=Livi%2C+R">Roberto Livi</a>, <a href="/search/physics?searchtype=author&query=Whittlesey%2C+P">P. Whittlesey</a> , et al. (7 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2005.12372v1-abstract-short" style="display: inline;"> The slow solar wind is typically characterized as having low Alfv茅nicity. However, Parker Solar Probe (PSP) observed predominately Alfv茅nic slow solar wind during several of its initial encounters. From its first encounter observations, about 55.3\% of the slow solar wind inside 0.25 au is highly Alfv茅nic ($|蟽_C| > 0.7$) at current solar minimum, which is much higher than the fraction of quiet-Sun… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2005.12372v1-abstract-full').style.display = 'inline'; document.getElementById('2005.12372v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2005.12372v1-abstract-full" style="display: none;"> The slow solar wind is typically characterized as having low Alfv茅nicity. However, Parker Solar Probe (PSP) observed predominately Alfv茅nic slow solar wind during several of its initial encounters. From its first encounter observations, about 55.3\% of the slow solar wind inside 0.25 au is highly Alfv茅nic ($|蟽_C| > 0.7$) at current solar minimum, which is much higher than the fraction of quiet-Sun-associated highly Alfv茅nic slow wind observed at solar maximum at 1 au. Intervals of slow solar wind with different Alfv茅nicities seem to show similar plasma characteristics and temperature anisotropy distributions. Some low Alfv茅nicity slow wind intervals even show high temperature anisotropies, because the slow wind may experience perpendicular heating as fast wind does when close to the Sun. This signature is confirmed by Wind spacecraft measurements as we track PSP observations to 1 au. Further, with nearly 15 years of Wind measurements, we find that the distributions of plasma characteristics, temperature anisotropy and helium abundance ratio ($N_伪/N_p$) are similar in slow winds with different Alfv茅nicities, but the distributions are different from those in the fast solar wind. Highly Alfv茅nic slow solar wind contains both helium-rich ($N_伪/N_p\sim0.045$) and helium-poor ($N_伪/N_p\sim0.015$) populations, implying it may originate from multiple source regions. These results suggest that highly Alfv茅nic slow solar wind shares similar temperature anisotropy and helium abundance properties with regular slow solar winds, and they thus should have multiple origins. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2005.12372v1-abstract-full').style.display = 'none'; document.getElementById('2005.12372v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 25 May, 2020; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> May 2020. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">submitted to ApJS, welcome comments</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2004.03009">arXiv:2004.03009</a> <span> [<a href="https://arxiv.org/pdf/2004.03009">pdf</a>, <a href="https://arxiv.org/format/2004.03009">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Space Physics">physics.space-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Solar and Stellar Astrophysics">astro-ph.SR</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.3847/1538-4365/ab86af">10.3847/1538-4365/ab86af <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Parker Solar Probe observations of proton beams simultaneous with ion-scale waves </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Verniero%2C+J+L">J. L. Verniero</a>, <a href="/search/physics?searchtype=author&query=Larson%2C+D+E">D. E. Larson</a>, <a href="/search/physics?searchtype=author&query=Livi%2C+R">R. Livi</a>, <a href="/search/physics?searchtype=author&query=Rahmati%2C+A">A. Rahmati</a>, <a href="/search/physics?searchtype=author&query=McManus%2C+M+D">M. D. McManus</a>, <a href="/search/physics?searchtype=author&query=Pyakurel%2C+P+S">P. Sharma Pyakurel</a>, <a href="/search/physics?searchtype=author&query=Klein%2C+K+G">K. G. Klein</a>, <a href="/search/physics?searchtype=author&query=Bowen%2C+T+A">T. A. Bowen</a>, <a href="/search/physics?searchtype=author&query=Bonnell%2C+J+W">J. W. Bonnell</a>, <a href="/search/physics?searchtype=author&query=Alterman%2C+B+L">B. L. Alterman</a>, <a href="/search/physics?searchtype=author&query=Whittlesey%2C+P+L">P. L. Whittlesey</a>, <a href="/search/physics?searchtype=author&query=Malaspina%2C+D+M">David M. Malaspina</a>, <a href="/search/physics?searchtype=author&query=Bale%2C+S+D">S. D. Bale</a>, <a href="/search/physics?searchtype=author&query=Kasper%2C+J+C">J. C. Kasper</a>, <a href="/search/physics?searchtype=author&query=Case%2C+A+W">A. W. Case</a>, <a href="/search/physics?searchtype=author&query=Goetz%2C+K">K. Goetz</a>, <a href="/search/physics?searchtype=author&query=Harvey%2C+P+R">P. R. Harvey</a>, <a href="/search/physics?searchtype=author&query=Korreck%2C+K+E">K. E. Korreck</a>, <a href="/search/physics?searchtype=author&query=MacDowall%2C+R+J">R. J. MacDowall</a>, <a href="/search/physics?searchtype=author&query=Pulupa%2C+M">M. Pulupa</a>, <a href="/search/physics?searchtype=author&query=Stevens%2C+M+L">M. L. Stevens</a>, <a href="/search/physics?searchtype=author&query=de+Wit%2C+T+D">T. Dudok de Wit</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2004.03009v1-abstract-short" style="display: inline;"> Parker Solar Probe (PSP), NASA's latest and closest mission to the Sun, is on a journey to investigate fundamental enigmas of the inner heliosphere. This paper reports initial observations made by the Solar Probe Analyzer for Ions (SPAN-I), one of the instruments in the Solar Wind Electrons Alphas and Protons (SWEAP) instrument suite. We address the presence of secondary proton beams in concert wi… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2004.03009v1-abstract-full').style.display = 'inline'; document.getElementById('2004.03009v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2004.03009v1-abstract-full" style="display: none;"> Parker Solar Probe (PSP), NASA's latest and closest mission to the Sun, is on a journey to investigate fundamental enigmas of the inner heliosphere. This paper reports initial observations made by the Solar Probe Analyzer for Ions (SPAN-I), one of the instruments in the Solar Wind Electrons Alphas and Protons (SWEAP) instrument suite. We address the presence of secondary proton beams in concert with ion-scale waves observed by FIELDS, the electromagnetic fields instrument suite. We show two events from PSP's 2nd orbit that demonstrate signatures consistent with wave-particle interactions. We showcase 3D velocity distribution functions (VDFs) measured by SPAN-I during times of strong wave power at ion-scales. From an initial instability analysis, we infer that the VDFs departed far enough away from local thermodynamic equilibrium (LTE) to provide sufficient free energy to locally generate waves. These events exemplify the types of instabilities that may be present and, as such, may guide future data analysis characterizing and distinguishing between different wave-particle interactions. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2004.03009v1-abstract-full').style.display = 'none'; document.getElementById('2004.03009v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 6 April, 2020; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> April 2020. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">24 pages, 9 figures, 2 tables</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2003.04016">arXiv:2003.04016</a> <span> [<a href="https://arxiv.org/pdf/2003.04016">pdf</a>, <a href="https://arxiv.org/format/2003.04016">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Solar and Stellar Astrophysics">astro-ph.SR</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Space Physics">physics.space-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.3847/1538-4357/ab7b7a">10.3847/1538-4357/ab7b7a <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Coronal Electron Temperature inferred from the Strahl Electrons in the Inner Heliosphere: Parker Solar Probe and Helios observations </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Bercic%2C+L">Laura Bercic</a>, <a href="/search/physics?searchtype=author&query=Larson%2C+D">Davin Larson</a>, <a href="/search/physics?searchtype=author&query=Whittlesey%2C+P">Phyllis Whittlesey</a>, <a href="/search/physics?searchtype=author&query=Maksimovic%2C+M">Milan Maksimovic</a>, <a href="/search/physics?searchtype=author&query=Badman%2C+S+T">Samuel T. Badman</a>, <a href="/search/physics?searchtype=author&query=Landi%2C+S">Simone Landi</a>, <a href="/search/physics?searchtype=author&query=Matteini%2C+L">Lorenzo Matteini</a>, <a href="/search/physics?searchtype=author&query=Bale%2C+S+D">Stuart. D. Bale</a>, <a href="/search/physics?searchtype=author&query=Bonnell%2C+J+W">John W. Bonnell</a>, <a href="/search/physics?searchtype=author&query=Case%2C+A+W">Anthony W. Case</a>, <a href="/search/physics?searchtype=author&query=de+Wit%2C+T+D">Thierry Dudok de Wit</a>, <a href="/search/physics?searchtype=author&query=Goetz%2C+K">Keith Goetz</a>, <a href="/search/physics?searchtype=author&query=Harvey%2C+P+R">Peter R. Harvey</a>, <a href="/search/physics?searchtype=author&query=Kasper%2C+J+C">Justin C. Kasper</a>, <a href="/search/physics?searchtype=author&query=Korreck%2C+K+E">Kelly E. Korreck</a>, <a href="/search/physics?searchtype=author&query=Livi%2C+R">Roberto Livi</a>, <a href="/search/physics?searchtype=author&query=MacDowall%2C+R+J">Robert J. MacDowall</a>, <a href="/search/physics?searchtype=author&query=Malaspina%2C+D+M">David M. Malaspina</a>, <a href="/search/physics?searchtype=author&query=Pulupa%2C+M">Marc Pulupa</a>, <a href="/search/physics?searchtype=author&query=Stevens%2C+M+L">Michael L. Stevens</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2003.04016v1-abstract-short" style="display: inline;"> The shape of the electron velocity distribution function plays an important role in the dynamics of the solar wind acceleration. Electrons are normally modelled with three components, the core, the halo, and the strahl. We investigate how well the fast strahl electrons in the inner heliosphere preserve the information about the coronal electron temperature at their origin. We analysed the data obt… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2003.04016v1-abstract-full').style.display = 'inline'; document.getElementById('2003.04016v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2003.04016v1-abstract-full" style="display: none;"> The shape of the electron velocity distribution function plays an important role in the dynamics of the solar wind acceleration. Electrons are normally modelled with three components, the core, the halo, and the strahl. We investigate how well the fast strahl electrons in the inner heliosphere preserve the information about the coronal electron temperature at their origin. We analysed the data obtained by two missions, Helios spanning the distances between 65 and 215 R$_S$, and Parker Solar Probe (PSP) reaching down to 35 R$_S$ during its first two orbits around the Sun. The electron strahl was characterised with two parameters, pitch-angle width (PAW), and the strahl parallel temperature (T$_{s\parallel}$). PSP observations confirm the already reported dependence of strahl PAW on core parallel plasma beta ($尾_{ec\parallel}$)\citep{Bercic2019}. Most of the strahl measured by PSP appear narrow with PAW reaching down to 30$^o$. The portion of the strahl velocity distribution function aligned with the magnetic field is for the measured energy range well described by a Maxwellian distribution function. T$_{s\parallel}$ was found to be anti-correlated with the solar wind velocity, and independent of radial distance. These observations imply that T$_{s\parallel}$ carries the information about the coronal electron temperature. The obtained values are in agreement with coronal temperatures measured using spectroscopy (David et al. 2998), and the inferred solar wind source regions during the first orbit of PSP agree with the predictions using a PFSS model (Bale et al. 2019, Badman et al. 2019). <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2003.04016v1-abstract-full').style.display = 'none'; document.getElementById('2003.04016v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 9 March, 2020; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> March 2020. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2002.09837">arXiv:2002.09837</a> <span> [<a href="https://arxiv.org/pdf/2002.09837">pdf</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Solar and Stellar Astrophysics">astro-ph.SR</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Space Physics">physics.space-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.3847/2041-8213/ab799c">10.3847/2041-8213/ab799c <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Sunward propagating whistler waves collocated with localized magnetic field holes in the solar wind: Parker Solar Probe observations at 35.7 Sun radii </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Agapitov%2C+O+V">O. V. Agapitov</a>, <a href="/search/physics?searchtype=author&query=de+Wit%2C+T+D">T. Dudok de Wit</a>, <a href="/search/physics?searchtype=author&query=Mozer%2C+F+S">F. S. Mozer</a>, <a href="/search/physics?searchtype=author&query=Bonnell%2C+J+W">J. W. Bonnell</a>, <a href="/search/physics?searchtype=author&query=Drake%2C+J+F">J. F. Drake</a>, <a href="/search/physics?searchtype=author&query=Malaspina%2C+D">D. Malaspina</a>, <a href="/search/physics?searchtype=author&query=Krasnoselskikh%2C+V">V. Krasnoselskikh</a>, <a href="/search/physics?searchtype=author&query=Bale%2C+S">S. Bale</a>, <a href="/search/physics?searchtype=author&query=Whittlesey%2C+P+L">P. L. Whittlesey</a>, <a href="/search/physics?searchtype=author&query=Case%2C+A+W">A. W. Case</a>, <a href="/search/physics?searchtype=author&query=Chaston%2C+C">C. Chaston</a>, <a href="/search/physics?searchtype=author&query=Froment%2C+C">C. Froment</a>, <a href="/search/physics?searchtype=author&query=Goetz%2C+K">K. Goetz</a>, <a href="/search/physics?searchtype=author&query=Goodrich%2C+K+A">K. A. Goodrich</a>, <a href="/search/physics?searchtype=author&query=Harvey%2C+P+R">P. R. Harvey</a>, <a href="/search/physics?searchtype=author&query=Kasper%2C+J+C">J. C. Kasper</a>, <a href="/search/physics?searchtype=author&query=Korreck%2C+K+E">K. E. Korreck</a>, <a href="/search/physics?searchtype=author&query=Larson%2C+D+E">D. E. Larson</a>, <a href="/search/physics?searchtype=author&query=Livi%2C+R">R. Livi</a>, <a href="/search/physics?searchtype=author&query=MacDowall%2C+R+J">R. J. MacDowall</a>, <a href="/search/physics?searchtype=author&query=Pulupa%2C+M">M. Pulupa</a>, <a href="/search/physics?searchtype=author&query=Revillet%2C+C">C. Revillet</a>, <a href="/search/physics?searchtype=author&query=Stevens%2C+M">M. Stevens</a>, <a href="/search/physics?searchtype=author&query=Wygant%2C+J+R">J. R. Wygant</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2002.09837v1-abstract-short" style="display: inline;"> Observations by the Parker Solar Probe mission of the solar wind at about 35.7 solar radii reveal the existence of whistler wave packets with frequencies below 0.1 f/fce (20-80 Hz in the spacecraft frame). These waves often coincide with local minima of the magnetic field magnitude or with sudden deflections of the magnetic field that are called switchbacks. Their sunward propagation leads to a si… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2002.09837v1-abstract-full').style.display = 'inline'; document.getElementById('2002.09837v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2002.09837v1-abstract-full" style="display: none;"> Observations by the Parker Solar Probe mission of the solar wind at about 35.7 solar radii reveal the existence of whistler wave packets with frequencies below 0.1 f/fce (20-80 Hz in the spacecraft frame). These waves often coincide with local minima of the magnetic field magnitude or with sudden deflections of the magnetic field that are called switchbacks. Their sunward propagation leads to a significant Doppler frequency downshift from 200-300 Hz to 20-80 Hz (from 0.2 f/fce to 0.5 f/fce). The polarization of these waves varies from quasi-parallel to significantly oblique with wave normal angles that are close to the resonance cone. Their peak amplitude can be as large as 2 to 4 nT. Such values represent approximately 10% of the background magnetic field, which is considerably more than what is observed at 1 a.u. Recent numerical studies show that such waves may potentially play a key role in breaking the heat flux and scattering the Strahl population of suprathermal electrons into a halo population. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2002.09837v1-abstract-full').style.display = 'none'; document.getElementById('2002.09837v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 23 February, 2020; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> February 2020. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2002.04080">arXiv:2002.04080</a> <span> [<a href="https://arxiv.org/pdf/2002.04080">pdf</a>, <a href="https://arxiv.org/format/2002.04080">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Instrumentation and Methods for Astrophysics">astro-ph.IM</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Solar and Stellar Astrophysics">astro-ph.SR</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Space Physics">physics.space-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.3847/1538-4365/ab7370">10.3847/1538-4365/ab7370 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> The Solar Probe ANalyzers -- Electrons on Parker Solar Probe </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Whittlesey%2C+P+L">Phyllis L Whittlesey</a>, <a href="/search/physics?searchtype=author&query=Larson%2C+D+E">Davin E Larson</a>, <a href="/search/physics?searchtype=author&query=Kasper%2C+J+C">Justin C Kasper</a>, <a href="/search/physics?searchtype=author&query=Halekas%2C+J">Jasper Halekas</a>, <a href="/search/physics?searchtype=author&query=Abatcha%2C+M">Mamuda Abatcha</a>, <a href="/search/physics?searchtype=author&query=Abiad%2C+R">Robert Abiad</a>, <a href="/search/physics?searchtype=author&query=Berthomier%2C+M">M. Berthomier</a>, <a href="/search/physics?searchtype=author&query=Case%2C+A+W">A. W. Case</a>, <a href="/search/physics?searchtype=author&query=Chen%2C+J">Jianxin Chen</a>, <a href="/search/physics?searchtype=author&query=Curtis%2C+D+W">David W Curtis</a>, <a href="/search/physics?searchtype=author&query=Dalton%2C+G">Gregory Dalton</a>, <a href="/search/physics?searchtype=author&query=Klein%2C+K+G">Kristopher G Klein</a>, <a href="/search/physics?searchtype=author&query=Korreck%2C+K+E">Kelly E Korreck</a>, <a href="/search/physics?searchtype=author&query=Livi%2C+R">Roberto Livi</a>, <a href="/search/physics?searchtype=author&query=Ludlam%2C+M">Michael Ludlam</a>, <a href="/search/physics?searchtype=author&query=Marckwordt%2C+M">Mario Marckwordt</a>, <a href="/search/physics?searchtype=author&query=Rahmati%2C+A">Ali Rahmati</a>, <a href="/search/physics?searchtype=author&query=Robinson%2C+M">Miles Robinson</a>, <a href="/search/physics?searchtype=author&query=Slagle%2C+A">Amanda Slagle</a>, <a href="/search/physics?searchtype=author&query=Stevens%2C+M+L">M L Stevens</a>, <a href="/search/physics?searchtype=author&query=Tiu%2C+C">Chris Tiu</a>, <a href="/search/physics?searchtype=author&query=Verniero%2C+J+L">J L Verniero</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2002.04080v1-abstract-short" style="display: inline;"> Electrostatic analyzers of different designs have been used since the earliest days of the space age, beginning with the very earliest solar wind measurements made by Mariner 2 en route to Venus in 1962. The Parker Solar Probe (PSP) mission, NASA's first dedicated mission to study the innermost reaches of the heliosphere, makes its thermal plasma measurements using a suite of instruments called th… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2002.04080v1-abstract-full').style.display = 'inline'; document.getElementById('2002.04080v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2002.04080v1-abstract-full" style="display: none;"> Electrostatic analyzers of different designs have been used since the earliest days of the space age, beginning with the very earliest solar wind measurements made by Mariner 2 en route to Venus in 1962. The Parker Solar Probe (PSP) mission, NASA's first dedicated mission to study the innermost reaches of the heliosphere, makes its thermal plasma measurements using a suite of instruments called the Solar Wind Electrons, Alphas, and Protons (SWEAP) investigation. SWEAP's electron Parker Solar Probe Analyzer (SPAN-E) instruments are a pair of top-hat electrostatic analyzers on PSP that are capable of measuring the electron distribution function in the solar wind from 2 eV to 30 keV. For the first time, in-situ measurements of thermal electrons provided by SPAN-E will help reveal the heating and acceleration mechanisms driving the evolution of the solar wind at the points of acceleration and heating, closer than ever before to the Sun. This paper details the design of the SPAN-E sensors and their operation, data formats, and measurement caveats from Parker Solar Probe's first two close encounters with the Sun. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2002.04080v1-abstract-full').style.display = 'none'; document.getElementById('2002.04080v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 10 February, 2020; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> February 2020. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">This draft has been Accepted in the Astrophysical Journal Special issue for Parker Solar Probe</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2001.08239">arXiv:2001.08239</a> <span> [<a href="https://arxiv.org/pdf/2001.08239">pdf</a>, <a href="https://arxiv.org/ps/2001.08239">ps</a>, <a href="https://arxiv.org/format/2001.08239">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Space Physics">physics.space-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Plasma Physics">physics.plasm-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.3847/1538-4365/ab672d">10.3847/1538-4365/ab672d <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> The Radial Dependence of Proton-scale Magnetic Spectral Break in Slow Solar Wind during PSP Encounter 2 </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Duan%2C+D">Die Duan</a>, <a href="/search/physics?searchtype=author&query=Bowen%2C+T+A">Trevor A. Bowen</a>, <a href="/search/physics?searchtype=author&query=Chen%2C+C+H+K">Christopher H. K. Chen</a>, <a href="/search/physics?searchtype=author&query=Mallet%2C+A">Alfred Mallet</a>, <a href="/search/physics?searchtype=author&query=He%2C+J">Jiansen He</a>, <a href="/search/physics?searchtype=author&query=Bale%2C+S+D">Stuart D. Bale</a>, <a href="/search/physics?searchtype=author&query=Vech%2C+D">Daniel Vech</a>, <a href="/search/physics?searchtype=author&query=Kasper%2C+J+C">J. C. Kasper</a>, <a href="/search/physics?searchtype=author&query=Pulupa%2C+M">Marc Pulupa</a>, <a href="/search/physics?searchtype=author&query=Bonnell%2C+J+W">John W. Bonnell</a>, <a href="/search/physics?searchtype=author&query=Case%2C+A+W">Anthony W. Case</a>, <a href="/search/physics?searchtype=author&query=de+Wit%2C+T+D">Thierry Dudok de Wit</a>, <a href="/search/physics?searchtype=author&query=Goetz%2C+K">Keith Goetz</a>, <a href="/search/physics?searchtype=author&query=Harvey%2C+P+R">Peter R. Harvey</a>, <a href="/search/physics?searchtype=author&query=Korreck%2C+K+E">Kelly E. Korreck</a>, <a href="/search/physics?searchtype=author&query=Larson%2C+D">Davin Larson</a>, <a href="/search/physics?searchtype=author&query=Livi%2C+R">Roberto Livi</a>, <a href="/search/physics?searchtype=author&query=MacDowall%2C+R+J">Robert J. MacDowall</a>, <a href="/search/physics?searchtype=author&query=Malaspina%2C+D+M">David M. Malaspina</a>, <a href="/search/physics?searchtype=author&query=Stevens%2C+M">Michael Stevens</a>, <a href="/search/physics?searchtype=author&query=Whittlesey%2C+P">Phyllis Whittlesey</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2001.08239v1-abstract-short" style="display: inline;"> Magnetic field fluctuations in the solar wind are commonly observed to follow a power law spectrum. Near proton-kinetic scales, a spectral break occurs which is commonly interpreted as a transition to kinetic turbulence. However, this transition is not yet entirely understood. By studying the scaling of the break with various plasma properties, it may be possible to constrain the processes leading… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2001.08239v1-abstract-full').style.display = 'inline'; document.getElementById('2001.08239v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2001.08239v1-abstract-full" style="display: none;"> Magnetic field fluctuations in the solar wind are commonly observed to follow a power law spectrum. Near proton-kinetic scales, a spectral break occurs which is commonly interpreted as a transition to kinetic turbulence. However, this transition is not yet entirely understood. By studying the scaling of the break with various plasma properties, it may be possible to constrain the processes leading to the onset of kinetic turbulence. Using data from Parker Solar Probe (\textit{PSP}), we measure the proton scale break over a range of heliocentric distances, enabling a measurement of the transition from inertial to kinetic scale turbulence under various plasma conditions. We find that the break frequency $f_b$ increases as the heliocentric distance $r$ decreases in the slow solar wind following a power law $f_b\sim r^{-1.11}$. We also compare this to the characteristic plasma ion scales to relate the break to the possible physical mechanisms occurring at this scale. The ratio between $f_b$ and $f_c$, the Doppler shifted ion cyclotron resonance scale, is approximately unity for all plasma $尾_p$. At high $尾_p$ the ratio between $f_b$ and $f_蟻$, the Doppler shifted gyroscale, is approximately unity; while at low $尾_p$ the ratio between $f_b$ and $f_d$, the Doppler shifted proton-inertial length is unity. Due to the large comparable Alfv茅n and solar wind speeds, we analyze these results using both the standard and modified Taylor hypothesis, demonstrating robust statistical results. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2001.08239v1-abstract-full').style.display = 'none'; document.getElementById('2001.08239v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 22 January, 2020; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> January 2020. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">Accepted by ApJS, Dec 14, 2019</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2001.06048">arXiv:2001.06048</a> <span> [<a href="https://arxiv.org/pdf/2001.06048">pdf</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Solar and Stellar Astrophysics">astro-ph.SR</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Plasma Physics">physics.plasm-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Space Physics">physics.space-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.3847/1538-4365/ab55ee">10.3847/1538-4365/ab55ee <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Parker Solar Probe In-Situ Observations of Magnetic Reconnection Exhausts During Encounter 1 </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Phan%2C+T+D">T. D. Phan</a>, <a href="/search/physics?searchtype=author&query=Bale%2C+S+D">S. D. Bale</a>, <a href="/search/physics?searchtype=author&query=Eastwood%2C+J+P">J. P. Eastwood</a>, <a href="/search/physics?searchtype=author&query=Lavraud%2C+B">B. Lavraud</a>, <a href="/search/physics?searchtype=author&query=Drake%2C+J+F">J. F. Drake</a>, <a href="/search/physics?searchtype=author&query=Oieroset%2C+M">M. Oieroset</a>, <a href="/search/physics?searchtype=author&query=Shay%2C+M+A">M. A. Shay</a>, <a href="/search/physics?searchtype=author&query=Pulupa%2C+M">M. Pulupa</a>, <a href="/search/physics?searchtype=author&query=Stevens%2C+M">M. Stevens</a>, <a href="/search/physics?searchtype=author&query=MacDowall%2C+R+J">R. J. MacDowall</a>, <a href="/search/physics?searchtype=author&query=Case%2C+A+W">A. W. Case</a>, <a href="/search/physics?searchtype=author&query=Larson%2C+D">D. Larson</a>, <a href="/search/physics?searchtype=author&query=Kasper%2C+J">J. Kasper</a>, <a href="/search/physics?searchtype=author&query=Whittlesey%2C+P">P. Whittlesey</a>, <a href="/search/physics?searchtype=author&query=Szabo%2C+A">A. Szabo</a>, <a href="/search/physics?searchtype=author&query=Korreck%2C+K+E">K. E. Korreck</a>, <a href="/search/physics?searchtype=author&query=Bonnell%2C+J+W">J. W. Bonnell</a>, <a href="/search/physics?searchtype=author&query=de+Wit%2C+T+D">T. Dudok de Wit</a>, <a href="/search/physics?searchtype=author&query=Goetz%2C+K">K. Goetz</a>, <a href="/search/physics?searchtype=author&query=Harvey%2C+P+R">P. R. Harvey</a>, <a href="/search/physics?searchtype=author&query=Horbury%2C+T+S">T. S. Horbury</a>, <a href="/search/physics?searchtype=author&query=Livi%2C+R">R. Livi</a>, <a href="/search/physics?searchtype=author&query=Malaspina%2C+D">D. Malaspina</a>, <a href="/search/physics?searchtype=author&query=Paulson%2C+K">K. Paulson</a>, <a href="/search/physics?searchtype=author&query=Raouafi%2C+N+E">N. E. Raouafi</a> , et al. (1 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2001.06048v1-abstract-short" style="display: inline;"> Magnetic reconnection in current sheets converts magnetic energy into particle energy. The process may play an important role in the acceleration and heating of the solar wind close to the Sun. Observations from Parker Solar Probe provide a new opportunity to study this problem, as it measures the solar wind at unprecedented close distances to the Sun. During the 1st orbit, PSP encountered a large… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2001.06048v1-abstract-full').style.display = 'inline'; document.getElementById('2001.06048v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2001.06048v1-abstract-full" style="display: none;"> Magnetic reconnection in current sheets converts magnetic energy into particle energy. The process may play an important role in the acceleration and heating of the solar wind close to the Sun. Observations from Parker Solar Probe provide a new opportunity to study this problem, as it measures the solar wind at unprecedented close distances to the Sun. During the 1st orbit, PSP encountered a large number of current sheets in the solar wind through perihelion at 35.7 solar radii. We performed a comprehensive survey of these current sheets and found evidence for 21 reconnection exhausts. These exhausts were observed in heliospheric current sheets, coronal mass ejections, and regular solar wind. However, we find that the majority of current sheets encountered around perihelion, where the magnetic field was strongest and plasma beta was lowest, were Alfv茅nic structures associated with bursty radial jets and these current sheets did not appear to be undergoing local reconnection. We examined conditions around current sheets to address why some current sheets reconnected, while others did not. A key difference appears to be the degree of plasma velocity shear across the current sheets: The median velocity shear for the 21 reconnection exhausts was 24% of the Alfv茅n velocity shear, whereas the median shear across 43 Alfv茅nic current sheets examined was 71% of the Alfv茅n velocity shear. This finding could suggest that large, albeit sub-Alfv茅nic, velocity shears suppress reconnection. An alternative interpretation is that the Alfv茅nic current sheets are isolated rotational discontinuities which do not undergo local reconnection. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2001.06048v1-abstract-full').style.display = 'none'; document.getElementById('2001.06048v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 16 January, 2020; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> January 2020. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">In Press (accepted by ApJS on 2019-11-08) This paper is part of the Parker Solar Probe ApJS Special Issue Current citation: Phan, T. D., S. D. Bale, J. P. Eastwood, et al. (2019), Parker Solar Probe In-Situ Observations of Magnetic Reconnection Exhausts During Encounter 1, ApJS., in press, doi: 10.3847/1538-4365/ab55ee</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2001.05081">arXiv:2001.05081</a> <span> [<a href="https://arxiv.org/pdf/2001.05081">pdf</a>, <a href="https://arxiv.org/format/2001.05081">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Solar and Stellar Astrophysics">astro-ph.SR</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Plasma Physics">physics.plasm-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Space Physics">physics.space-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1103/PhysRevLett.125.025102">10.1103/PhysRevLett.125.025102 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Inner-Heliosphere Signatures of Ion-Scale Dissipation and Nonlinear Interaction </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Bowen%2C+T+A">Trevor A. Bowen</a>, <a href="/search/physics?searchtype=author&query=Mallet%2C+A">Alfred Mallet</a>, <a href="/search/physics?searchtype=author&query=Bale%2C+S+D">Stuart D. Bale</a>, <a href="/search/physics?searchtype=author&query=Bonnell%2C+J+W">J. W. Bonnell</a>, <a href="/search/physics?searchtype=author&query=Case%2C+A+W">Anthony W. Case</a>, <a href="/search/physics?searchtype=author&query=Chandran%2C+B+D+G">Benjamin D. G. Chandran</a>, <a href="/search/physics?searchtype=author&query=Chasapis%2C+A">Alexandros Chasapis</a>, <a href="/search/physics?searchtype=author&query=Chen%2C+C+H+K">Christopher H. K. Chen</a>, <a href="/search/physics?searchtype=author&query=Duan%2C+D">Die Duan</a>, <a href="/search/physics?searchtype=author&query=de+Wit%2C+T+D">Thierry Dudok de Wit</a>, <a href="/search/physics?searchtype=author&query=Goetz%2C+K">Keith Goetz</a>, <a href="/search/physics?searchtype=author&query=Halekas%2C+J">Jasper Halekas</a>, <a href="/search/physics?searchtype=author&query=Harvey%2C+P+R">Peter R. Harvey</a>, <a href="/search/physics?searchtype=author&query=Kasper%2C+J+C">J. C. Kasper</a>, <a href="/search/physics?searchtype=author&query=Korreck%2C+K+E">Kelly E. Korreck</a>, <a href="/search/physics?searchtype=author&query=Larson%2C+D">Davin Larson</a>, <a href="/search/physics?searchtype=author&query=Livi%2C+R">Roberto Livi</a>, <a href="/search/physics?searchtype=author&query=MacDowall%2C+R+J">Robert J. MacDowall</a>, <a href="/search/physics?searchtype=author&query=Malaspina%2C+D+M">David M. Malaspina</a>, <a href="/search/physics?searchtype=author&query=Pulupa%2C+M">Marc Pulupa</a>, <a href="/search/physics?searchtype=author&query=Stevens%2C+M">Michael Stevens</a>, <a href="/search/physics?searchtype=author&query=Whittlesey%2C+P">Phyllis Whittlesey</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2001.05081v1-abstract-short" style="display: inline;"> We perform a statistical study of the turbulent power spectrum at inertial and kinetic scales observed during the first perihelion encounter of Parker Solar Probe. We find that often there is an extremely steep scaling range of the power spectrum just above the ion-kinetic scales, similar to prior observations at 1 AU, with a power-law index of around $-4$. Based on our measurements, we demonstrat… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2001.05081v1-abstract-full').style.display = 'inline'; document.getElementById('2001.05081v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2001.05081v1-abstract-full" style="display: none;"> We perform a statistical study of the turbulent power spectrum at inertial and kinetic scales observed during the first perihelion encounter of Parker Solar Probe. We find that often there is an extremely steep scaling range of the power spectrum just above the ion-kinetic scales, similar to prior observations at 1 AU, with a power-law index of around $-4$. Based on our measurements, we demonstrate that either a significant ($>50\%$) fraction of the total turbulent energy flux is dissipated in this range of scales, or the characteristic nonlinear interaction time of the turbulence decreases dramatically from the expectation based solely on the dispersive nature of nonlinearly interacting kinetic Alfv茅n waves. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2001.05081v1-abstract-full').style.display = 'none'; document.getElementById('2001.05081v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 14 January, 2020; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> January 2020. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Phys. Rev. Lett. 125, 025102 (2020) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2001.03476">arXiv:2001.03476</a> <span> [<a href="https://arxiv.org/pdf/2001.03476">pdf</a>, <a href="https://arxiv.org/format/2001.03476">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Solar and Stellar Astrophysics">astro-ph.SR</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Earth and Planetary Astrophysics">astro-ph.EP</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Plasma Physics">physics.plasm-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Space Physics">physics.space-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.3847/1538-4365/ab65bd">10.3847/1538-4365/ab65bd <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Density Fluctuations in the Solar Wind Based on Type III Radio Bursts Observed by Parker Solar Probe </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Krupar%2C+V">Vratislav Krupar</a>, <a href="/search/physics?searchtype=author&query=Szabo%2C+A">Adam Szabo</a>, <a href="/search/physics?searchtype=author&query=Maksimovic%2C+M">Milan Maksimovic</a>, <a href="/search/physics?searchtype=author&query=Kruparova%2C+O">Oksana Kruparova</a>, <a href="/search/physics?searchtype=author&query=Kontar%2C+E+P">Eduard P. Kontar</a>, <a href="/search/physics?searchtype=author&query=Balmaceda%2C+L+A">Laura A. Balmaceda</a>, <a href="/search/physics?searchtype=author&query=Bonnin%2C+X">Xavier Bonnin</a>, <a href="/search/physics?searchtype=author&query=Bale%2C+S+D">Stuart D. Bale</a>, <a href="/search/physics?searchtype=author&query=Pulupa%2C+M">Marc Pulupa</a>, <a href="/search/physics?searchtype=author&query=Malaspina%2C+D+M">David M. Malaspina</a>, <a href="/search/physics?searchtype=author&query=Bonnell%2C+J+W">John W. Bonnell</a>, <a href="/search/physics?searchtype=author&query=Harvey%2C+P+R">Peter R. Harvey</a>, <a href="/search/physics?searchtype=author&query=Goetz%2C+K">Keith Goetz</a>, <a href="/search/physics?searchtype=author&query=de+Wit%2C+T+D">Thierry Dudok de Wit</a>, <a href="/search/physics?searchtype=author&query=MacDowall%2C+R+J">Robert J. MacDowall</a>, <a href="/search/physics?searchtype=author&query=Kasper%2C+J+C">Justin C. Kasper</a>, <a href="/search/physics?searchtype=author&query=Case%2C+A+W">Anthony W. Case</a>, <a href="/search/physics?searchtype=author&query=Korreck%2C+K+E">Kelly E. Korreck</a>, <a href="/search/physics?searchtype=author&query=Larson%2C+D+E">Davin E. Larson</a>, <a href="/search/physics?searchtype=author&query=Livi%2C+R">Roberto Livi</a>, <a href="/search/physics?searchtype=author&query=Stevens%2C+M+L">Michael L. Stevens</a>, <a href="/search/physics?searchtype=author&query=Whittlesey%2C+P+L">Phyllis L. Whittlesey</a>, <a href="/search/physics?searchtype=author&query=Hegedus%2C+A+M">Alexander M. Hegedus</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2001.03476v1-abstract-short" style="display: inline;"> Radio waves are strongly scattered in the solar wind, so that their apparent sources seem to be considerably larger and shifted than the actual ones. Since the scattering depends on the spectrum of density turbulence, better understanding of the radio wave propagation provides indirect information on the relative density fluctuations $蔚=\langle未n\rangle/\langle n\rangle$ at the effective turbulenc… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2001.03476v1-abstract-full').style.display = 'inline'; document.getElementById('2001.03476v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2001.03476v1-abstract-full" style="display: none;"> Radio waves are strongly scattered in the solar wind, so that their apparent sources seem to be considerably larger and shifted than the actual ones. Since the scattering depends on the spectrum of density turbulence, better understanding of the radio wave propagation provides indirect information on the relative density fluctuations $蔚=\langle未n\rangle/\langle n\rangle$ at the effective turbulence scale length. Here, we have analyzed 30 type III bursts detected by Parker Solar Probe (PSP). For the first time, we have retrieved type III burst decay times $蟿_{\rm{d}}$ between 1 MHz and 10 MHz thanks to an unparalleled temporal resolution of PSP. We observed a significant deviation in a power-law slope for frequencies above 1 MHz when compared to previous measurements below 1 MHz by the twin-spacecraft Solar TErrestrial RElations Observatory (STEREO) mission. We note that altitudes of radio bursts generated at 1 MHz roughly coincide with an expected location of the Alfv茅n point, where the solar wind becomes super-Alfv茅nic. By comparing PSP observations and Monte Carlo simulations, we predict relative density fluctuations $蔚$ at the effective turbulence scale length at radial distances between 2.5$R_\odot$ and 14$R_\odot$ to range from $0.22$ and $0.09$. Finally, we calculated relative density fluctuations $蔚$ measured in situ by PSP at a radial distance from the Sun of $35.7$~$R_\odot$ during the perihelion \#1, and the perihelion \#2 to be $0.07$ and $0.06$, respectively. It is in a very good agreement with previous STEREO predictions ($蔚=0.06-0.07$) obtained by remote measurements of radio sources generated at this radial distance. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2001.03476v1-abstract-full').style.display = 'none'; document.getElementById('2001.03476v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 10 January, 2020; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> January 2020. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">12 pages, 10 figures, accepted for publication in ApJS</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1912.08244">arXiv:1912.08244</a> <span> [<a href="https://arxiv.org/pdf/1912.08244">pdf</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Space Physics">physics.space-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Solar and Stellar Astrophysics">astro-ph.SR</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.3847/1538-4365/ab4c38">10.3847/1538-4365/ab4c38 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Energetic Particle Increases Associated with Stream Interaction Regions </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Cohen%2C+C+M+S">C. M. S. Cohen</a>, <a href="/search/physics?searchtype=author&query=Christian%2C+E+R">E. R. Christian</a>, <a href="/search/physics?searchtype=author&query=Cummings%2C+A+C">A. C. Cummings</a>, <a href="/search/physics?searchtype=author&query=Davis%2C+A+J">A. J. Davis</a>, <a href="/search/physics?searchtype=author&query=Desai%2C+M+I">M. I. Desai</a>, <a href="/search/physics?searchtype=author&query=Giacalone%2C+J">J. Giacalone</a>, <a href="/search/physics?searchtype=author&query=Hill%2C+M+E">M. E. Hill</a>, <a href="/search/physics?searchtype=author&query=Joyce%2C+C+J">C. J. Joyce</a>, <a href="/search/physics?searchtype=author&query=Labrador%2C+A+W">A. W. Labrador</a>, <a href="/search/physics?searchtype=author&query=Leske%2C+R+A">R. A. Leske</a>, <a href="/search/physics?searchtype=author&query=Matthaeus%2C+W+H">W. H. Matthaeus</a>, <a href="/search/physics?searchtype=author&query=McComas%2C+D+J">D. J. McComas</a>, <a href="/search/physics?searchtype=author&query=McNutt%2C%2C+R+L">R. L. McNutt, Jr.</a>, <a href="/search/physics?searchtype=author&query=Mewaldt%2C+R+A">R. A. Mewaldt</a>, <a href="/search/physics?searchtype=author&query=Mitchell%2C+D+G">D. G. Mitchell</a>, <a href="/search/physics?searchtype=author&query=Rankin%2C+J+S">J. S. Rankin</a>, <a href="/search/physics?searchtype=author&query=Roelof%2C+E+C">E. C. Roelof</a>, <a href="/search/physics?searchtype=author&query=Schwadron%2C+N+A">N. A. Schwadron</a>, <a href="/search/physics?searchtype=author&query=Stone%2C+E+C">E. C. Stone</a>, <a href="/search/physics?searchtype=author&query=Szalay%2C+J+R">J. R. Szalay</a>, <a href="/search/physics?searchtype=author&query=Wiedenbeck%2C+M+E">M. E. Wiedenbeck</a>, <a href="/search/physics?searchtype=author&query=Allen%2C+R+C">R. C. Allen</a>, <a href="/search/physics?searchtype=author&query=Ho%2C+G+C">G. C. Ho</a>, <a href="/search/physics?searchtype=author&query=Jian%2C+L+K">L. K. Jian</a>, <a href="/search/physics?searchtype=author&query=Lario%2C+D">D. Lario</a> , et al. (12 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1912.08244v2-abstract-short" style="display: inline;"> The Parker Solar Probe was launched on 2018 August 12 and completed its second orbit on 2019 June 19 with perihelion of 35.7 solar radii. During this time, the Energetic particle Instrument-Hi (EPI-Hi, one of the two energetic particle instruments comprising the Integrated Science Investigation of the Sun, ISOIS) measured seven proton intensity increases associated with stream interaction regions… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1912.08244v2-abstract-full').style.display = 'inline'; document.getElementById('1912.08244v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1912.08244v2-abstract-full" style="display: none;"> The Parker Solar Probe was launched on 2018 August 12 and completed its second orbit on 2019 June 19 with perihelion of 35.7 solar radii. During this time, the Energetic particle Instrument-Hi (EPI-Hi, one of the two energetic particle instruments comprising the Integrated Science Investigation of the Sun, ISOIS) measured seven proton intensity increases associated with stream interaction regions (SIRs), two of which appear to be occurring in the same region corotating with the Sun. The events are relatively weak, with observed proton spectra extending to only a few MeV and lasting for a few days. The proton spectra are best characterized by power laws with indices ranging from -4.3 to -6.5, generally softer than events associated with SIRs observed at 1 au and beyond. Helium spectra were also obtained with similar indices, allowing He/H abundance ratios to be calculated for each event. We find values of 0.016-0.031, which are consistent with ratios obtained previously for corotating interaction region events with fast solar wind < 600 km s-1. Using the observed solar wind data combined with solar wind simulations, we study the solar wind structures associated with these events and identify additional spacecraft near 1 au appropriately positioned to observe the same structures after some corotation. Examination of the energetic particle observations from these spacecraft yields two events that may correspond to the energetic particle increases seen by EPI-Hi earlier. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1912.08244v2-abstract-full').style.display = 'none'; document.getElementById('1912.08244v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 3 February, 2020; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 17 December, 2019; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> December 2019. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1912.07823">arXiv:1912.07823</a> <span> [<a href="https://arxiv.org/pdf/1912.07823">pdf</a>, <a href="https://arxiv.org/format/1912.07823">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Space Physics">physics.space-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Solar and Stellar Astrophysics">astro-ph.SR</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.3847/1538-4365/ab6dce">10.3847/1538-4365/ab6dce <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Cross Helicity Reversals In Magnetic Switchbacks </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=McManus%2C+M+D">Michael D. McManus</a>, <a href="/search/physics?searchtype=author&query=Bowen%2C+T+A">Trevor A. Bowen</a>, <a href="/search/physics?searchtype=author&query=Mallet%2C+A">Alfred Mallet</a>, <a href="/search/physics?searchtype=author&query=Chen%2C+C+H+K">Christopher H. K. Chen</a>, <a href="/search/physics?searchtype=author&query=Chandran%2C+B+D+G">Benjamin D. G. Chandran</a>, <a href="/search/physics?searchtype=author&query=Bale%2C+S+D">Stuart D. Bale</a>, <a href="/search/physics?searchtype=author&query=Larson%2C+D+E">Davin E. Larson</a>, <a href="/search/physics?searchtype=author&query=de+Wit%2C+T+D">Thierry Dudok de Wit</a>, <a href="/search/physics?searchtype=author&query=Kasper%2C+J+C">Justin C. Kasper</a>, <a href="/search/physics?searchtype=author&query=Stevens%2C+M">Michael Stevens</a>, <a href="/search/physics?searchtype=author&query=Whittlesey%2C+P">Phyllis Whittlesey</a>, <a href="/search/physics?searchtype=author&query=Livi%2C+R">Roberto Livi</a>, <a href="/search/physics?searchtype=author&query=Korreck%2C+K+E">Kelly E. Korreck</a>, <a href="/search/physics?searchtype=author&query=Goetz%2C+K">Keith Goetz</a>, <a href="/search/physics?searchtype=author&query=Harvey%2C+P+R">Peter R. Harvey</a>, <a href="/search/physics?searchtype=author&query=Pulupa%2C+M">Marc Pulupa</a>, <a href="/search/physics?searchtype=author&query=MacDowall%2C+R+J">Robert J. MacDowall</a>, <a href="/search/physics?searchtype=author&query=Malaspina%2C+D+M">David M. Malaspina</a>, <a href="/search/physics?searchtype=author&query=Case%2C+A+W">Anthony W. Case</a>, <a href="/search/physics?searchtype=author&query=Bonnell%2C+J+W">John W. Bonnell</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1912.07823v1-abstract-short" style="display: inline;"> We consider 2D joint distributions of normalised residual energy $蟽_r(s,t)$ and cross helicity $蟽_c(s,t)$ during one day of Parker Solar Probe's (PSP's) first encounter as a function of wavelet scale $s$. The broad features of the distributions are similar to previous observations made by HELIOS in slow solar wind, namely well correlated and fairly Alfv茅nic, except for a population with negative c… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1912.07823v1-abstract-full').style.display = 'inline'; document.getElementById('1912.07823v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1912.07823v1-abstract-full" style="display: none;"> We consider 2D joint distributions of normalised residual energy $蟽_r(s,t)$ and cross helicity $蟽_c(s,t)$ during one day of Parker Solar Probe's (PSP's) first encounter as a function of wavelet scale $s$. The broad features of the distributions are similar to previous observations made by HELIOS in slow solar wind, namely well correlated and fairly Alfv茅nic, except for a population with negative cross helicity which is seen at shorter wavelet scales. We show that this population is due to the presence of magnetic switchbacks, brief periods where the magnetic field polarity reverses. Such switchbacks have been observed before, both in HELIOS data and in Ulysses data in the polar solar wind. Their abundance and short timescales as seen by PSP in its first encounter is a new observation, and their precise origin is still unknown. By analysing these MHD invariants as a function of wavelet scale we show that MHD waves do indeed follow the local mean magnetic field through switchbacks, with net Elsasser flux propagating inward during the field reversal, and that they therefore must be local kinks in the magnetic field and not due to small regions of opposite polarity on the surface of the Sun. Such observations are important to keep in mind as computing cross helicity without taking into account the effect of switchbacks may result in spurious underestimation of $蟽_c$ as PSP gets closer to the Sun in later orbits. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1912.07823v1-abstract-full').style.display = 'none'; document.getElementById('1912.07823v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 17 December, 2019; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> December 2019. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1912.07719">arXiv:1912.07719</a> <span> [<a href="https://arxiv.org/pdf/1912.07719">pdf</a>, <a href="https://arxiv.org/format/1912.07719">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Space Physics">physics.space-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Plasma Physics">physics.plasm-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.3847/1538-4365/ab60a2">10.3847/1538-4365/ab60a2 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Kinetic Scale Spectral Features of Cross Helicity and Residual Energy in the Inner Heliosphere </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Vech%2C+D">Daniel Vech</a>, <a href="/search/physics?searchtype=author&query=Kasper%2C+J+C">Justin C. Kasper</a>, <a href="/search/physics?searchtype=author&query=Klein%2C+K+G">Kristopher G. Klein</a>, <a href="/search/physics?searchtype=author&query=Huang%2C+J">Jia Huang</a>, <a href="/search/physics?searchtype=author&query=Stevens%2C+M+L">Michael L. Stevens</a>, <a href="/search/physics?searchtype=author&query=Chen%2C+C+H+K">Christopher H. K. Chen</a>, <a href="/search/physics?searchtype=author&query=Case%2C+A+W">Anthony W. Case</a>, <a href="/search/physics?searchtype=author&query=Korreck%2C+K">Kelly Korreck</a>, <a href="/search/physics?searchtype=author&query=Bale%2C+S+D">Stuart D. Bale</a>, <a href="/search/physics?searchtype=author&query=Bowen%2C+T+A">Trevor A. Bowen</a>, <a href="/search/physics?searchtype=author&query=Whittlesey%2C+P+L">Phyllis L. Whittlesey</a>, <a href="/search/physics?searchtype=author&query=Livi%2C+R">Roberto Livi</a>, <a href="/search/physics?searchtype=author&query=Larson%2C+D+E">Davin E. Larson</a>, <a href="/search/physics?searchtype=author&query=Malaspina%2C+D">David Malaspina</a>, <a href="/search/physics?searchtype=author&query=Pulupa%2C+M">Marc Pulupa</a>, <a href="/search/physics?searchtype=author&query=Bonnell%2C+J">John Bonnell</a>, <a href="/search/physics?searchtype=author&query=Harvey%2C+P">Peter Harvey</a>, <a href="/search/physics?searchtype=author&query=Goetz%2C+K">Keith Goetz</a>, <a href="/search/physics?searchtype=author&query=de+Wit%2C+T+D">Thierry Dudok de Wit</a>, <a href="/search/physics?searchtype=author&query=MacDowall%2C+R">Robert MacDowall</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1912.07719v1-abstract-short" style="display: inline;"> In this Paper, we present the first results from the Flux Angle operation mode of the Faraday Cup instrument onboard Parker Solar Probe. The Flux Angle mode allows rapid measurements of phase space density fluctuations close to the peak of the proton velocity distribution function with a cadence of 293 Hz. This approach provides an invaluable tool for understanding kinetic scale turbulence in the… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1912.07719v1-abstract-full').style.display = 'inline'; document.getElementById('1912.07719v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1912.07719v1-abstract-full" style="display: none;"> In this Paper, we present the first results from the Flux Angle operation mode of the Faraday Cup instrument onboard Parker Solar Probe. The Flux Angle mode allows rapid measurements of phase space density fluctuations close to the peak of the proton velocity distribution function with a cadence of 293 Hz. This approach provides an invaluable tool for understanding kinetic scale turbulence in the solar wind and solar corona. We describe a technique to convert the phase space density fluctuations into vector velocity components and compute several turbulence parameters such as spectral index, residual energy and cross helicity during two intervals the Flux Angle mode was used in Parker Solar Probe's first encounter at 0.174 AU distance from the Sun. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1912.07719v1-abstract-full').style.display = 'none'; document.getElementById('1912.07719v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 16 December, 2019; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> December 2019. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">Accepted for publication in ApJS</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1912.07181">arXiv:1912.07181</a> <span> [<a href="https://arxiv.org/pdf/1912.07181">pdf</a>, <a href="https://arxiv.org/format/1912.07181">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Space Physics">physics.space-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Solar and Stellar Astrophysics">astro-ph.SR</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Plasma Physics">physics.plasm-ph</span> </div> </div> <p class="title is-5 mathjax"> Measures of Scale Dependent Alfv茅nicity in the First PSP Solar Encounter </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Parashar%2C+T+N">T. N. Parashar</a>, <a href="/search/physics?searchtype=author&query=Goldstein%2C+M+L">M. L. Goldstein</a>, <a href="/search/physics?searchtype=author&query=Maruca%2C+B+A">B. A. Maruca</a>, <a href="/search/physics?searchtype=author&query=Matthaeus%2C+W+H">W. H. Matthaeus</a>, <a href="/search/physics?searchtype=author&query=Ruffolo%2C+D">D. Ruffolo</a>, <a href="/search/physics?searchtype=author&query=Bandyopadhyay%2C+R">R. Bandyopadhyay</a>, <a href="/search/physics?searchtype=author&query=Chhiber%2C+R">R. Chhiber</a>, <a href="/search/physics?searchtype=author&query=Chasapis%2C+A">A. Chasapis</a>, <a href="/search/physics?searchtype=author&query=Qudsi%2C+R">R. Qudsi</a>, <a href="/search/physics?searchtype=author&query=Vech%2C+D">D. Vech</a>, <a href="/search/physics?searchtype=author&query=Roberts%2C+D+A">D. A. Roberts</a>, <a href="/search/physics?searchtype=author&query=Bale%2C+S+D">S. D. Bale</a>, <a href="/search/physics?searchtype=author&query=Bonnell%2C+J+W">J. W. Bonnell</a>, <a href="/search/physics?searchtype=author&query=de+Wit%2C+T+D">T. Dudok de Wit</a>, <a href="/search/physics?searchtype=author&query=Goetz%2C+K">K. Goetz</a>, <a href="/search/physics?searchtype=author&query=Harvey%2C+P+R">P. R. Harvey</a>, <a href="/search/physics?searchtype=author&query=MacDowall%2C+R+J">R. J. MacDowall</a>, <a href="/search/physics?searchtype=author&query=Malaspina%2C+D">D. Malaspina</a>, <a href="/search/physics?searchtype=author&query=Pulupa%2C+M">M. Pulupa</a>, <a href="/search/physics?searchtype=author&query=Kasper%2C+J+C">J. C. Kasper</a>, <a href="/search/physics?searchtype=author&query=Korreck%2C+K+E">K. E. Korreck</a>, <a href="/search/physics?searchtype=author&query=Case%2C+A+W">A. W. Case</a>, <a href="/search/physics?searchtype=author&query=Stevens%2C+M">M. Stevens</a>, <a href="/search/physics?searchtype=author&query=Whittlesey%2C+P">P. Whittlesey</a>, <a href="/search/physics?searchtype=author&query=Larson%2C+D">D. Larson</a> , et al. (3 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1912.07181v1-abstract-short" style="display: inline;"> The solar wind shows periods of highly Alfv茅nic activity, where velocity fluctuations and magnetic fluctuations are aligned or anti-aligned with each other. It is generally agreed that solar wind plasma velocity and magnetic field fluctuations observed by Parker Solar Probe (PSP) during the first encounter are mostly highly Alfv茅nic. However, quantitative measures of Alfv茅nicity are needed to unde… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1912.07181v1-abstract-full').style.display = 'inline'; document.getElementById('1912.07181v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1912.07181v1-abstract-full" style="display: none;"> The solar wind shows periods of highly Alfv茅nic activity, where velocity fluctuations and magnetic fluctuations are aligned or anti-aligned with each other. It is generally agreed that solar wind plasma velocity and magnetic field fluctuations observed by Parker Solar Probe (PSP) during the first encounter are mostly highly Alfv茅nic. However, quantitative measures of Alfv茅nicity are needed to understand how the characterization of these fluctuations compares with standard measures from prior missions in the inner and outer heliosphere, in fast wind and slow wind, and at high and low latitudes. To investigate this issue, we employ several measures to quantify the extent of Alfv茅nicity -- the Alfv茅n ratio $r_A$, {normalized} cross helicity $蟽_c$, {normalized} residual energy $蟽_r$, and the cosine of angle between velocity and magnetic fluctuations $\cos胃_{vb}$. We show that despite the overall impression that the Alfv茅nicity is large in the solar wind sampled by PSP during the first encounter, during some intervals the cross helicity starts decreasing at very large scales. These length-scales (often $> 1000 d_i$) are well inside inertial range, and therefore, the suppression of cross helicity at these scales cannot be attributed to kinetic physics. This drop at large scales could potentially be explained by large-scale shears present in the inner heliosphere sampled by PSP. In some cases, despite the cross helicity being constant down to the noise floor, the residual energy decreases with scale in the inertial range. These results suggest that it is important to consider all these measures to quantify Alfv茅nicity. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1912.07181v1-abstract-full').style.display = 'none'; document.getElementById('1912.07181v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 15 December, 2019; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> December 2019. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">Submitted to special issue of ApJ for Parker Solar Probe</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1912.06793">arXiv:1912.06793</a> <span> [<a href="https://arxiv.org/pdf/1912.06793">pdf</a>, <a href="https://arxiv.org/format/1912.06793">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Space Physics">physics.space-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Solar and Stellar Astrophysics">astro-ph.SR</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.3847/1538-4365/ab4c3b">10.3847/1538-4365/ab4c3b <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Plasma Waves near the Electron Cyclotron Frequency in the near-Sun Solar Wind </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Malaspina%2C+D+M">David M. Malaspina</a>, <a href="/search/physics?searchtype=author&query=Halekas%2C+J">Jasper Halekas</a>, <a href="/search/physics?searchtype=author&query=Bercic%2C+L">Laura Bercic</a>, <a href="/search/physics?searchtype=author&query=Larson%2C+D">Davin Larson</a>, <a href="/search/physics?searchtype=author&query=Whittlesey%2C+P">Phyllis Whittlesey</a>, <a href="/search/physics?searchtype=author&query=Bale%2C+S+D">Stuart D. Bale</a>, <a href="/search/physics?searchtype=author&query=Bonnell%2C+J+W">John W. Bonnell</a>, <a href="/search/physics?searchtype=author&query=de+Wit%2C+T+D">Thierry Dudok de Wit</a>, <a href="/search/physics?searchtype=author&query=Ergun%2C+R+E">Robert E. Ergun</a>, <a href="/search/physics?searchtype=author&query=Howes%2C+G">Gregory Howes</a>, <a href="/search/physics?searchtype=author&query=Goetz%2C+K">Keith Goetz</a>, <a href="/search/physics?searchtype=author&query=Goodrich%2C+K">Katherine Goodrich</a>, <a href="/search/physics?searchtype=author&query=Harvey%2C+P+R">Peter R. Harvey</a>, <a href="/search/physics?searchtype=author&query=MacDowall%2C+R+J">Robert J. MacDowall</a>, <a href="/search/physics?searchtype=author&query=Pulupa%2C+M">Marc Pulupa</a>, <a href="/search/physics?searchtype=author&query=Case%2C+A+W">Anthony W. Case</a>, <a href="/search/physics?searchtype=author&query=Kasper%2C+J+C">Justin C. Kasper</a>, <a href="/search/physics?searchtype=author&query=Korreck%2C+K+E">Kelly E. Korreck</a>, <a href="/search/physics?searchtype=author&query=Livi%2C+R">Roberto Livi</a>, <a href="/search/physics?searchtype=author&query=Stevens%2C+M+L">Michael L. Stevens</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1912.06793v2-abstract-short" style="display: inline;"> Data from the first two orbits of the Sun by Parker Solar Probe reveal that the solar wind sunward of 50 solar radii is replete with plasma waves and instabilities. One of the most prominent plasma wave power enhancements in this region appears near the electron cyclotron frequency (f_ce). Most of this wave power is concentrated in electric field fluctuations near 0.7 f_ce and f_ce, with strong ha… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1912.06793v2-abstract-full').style.display = 'inline'; document.getElementById('1912.06793v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1912.06793v2-abstract-full" style="display: none;"> Data from the first two orbits of the Sun by Parker Solar Probe reveal that the solar wind sunward of 50 solar radii is replete with plasma waves and instabilities. One of the most prominent plasma wave power enhancements in this region appears near the electron cyclotron frequency (f_ce). Most of this wave power is concentrated in electric field fluctuations near 0.7 f_ce and f_ce, with strong harmonics of both frequencies extending above f_ce. At least two distinct, often concurrent, wave modes are observed, preliminarily identified as electrostatic whistler-mode waves and electron Bernstein waves. Wave intervals range in duration from a few seconds to hours. Both the amplitudes and number of detections of these near-f_ce waves increase significantly with decreasing distance to the Sun, suggesting that they play an important role in the evolution of electron populations in the near-Sun solar wind. Correlations are found between the detection of these waves and properties of solar wind electron populations, including electron core drift, implying that these waves play a role in regulating the heat flux carried by solar wind electrons. Observation of these near-f_ce waves is found to be strongly correlated with near-radial solar wind magnetic field configurations with low levels of magnetic turbulence. A scenario for the growth of these waves is presented which implies that regions of low-turbulence near-radial magnetic field are a prominent feature of solar wind structure near the Sun. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1912.06793v2-abstract-full').style.display = 'none'; document.getElementById('1912.06793v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 21 April, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 14 December, 2019; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> December 2019. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1912.05483">arXiv:1912.05483</a> <span> [<a href="https://arxiv.org/pdf/1912.05483">pdf</a>, <a href="https://arxiv.org/format/1912.05483">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Space Physics">physics.space-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Plasma Physics">physics.plasm-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.3847/1538-4365/ab5c19">10.3847/1538-4365/ab5c19 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Observations of heating along intermittent structures in the inner heliosphere from PSP data </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Qudsi%2C+R+A">R. A. Qudsi</a>, <a href="/search/physics?searchtype=author&query=Maruca%2C+B+A">B. A. Maruca</a>, <a href="/search/physics?searchtype=author&query=Matthaeus%2C+W+H">W. H. Matthaeus</a>, <a href="/search/physics?searchtype=author&query=Parashar%2C+T+N">T. N. Parashar</a>, <a href="/search/physics?searchtype=author&query=Bandyopadhyay%2C+R">Riddhi Bandyopadhyay</a>, <a href="/search/physics?searchtype=author&query=Chhiber%2C+R">R. Chhiber</a>, <a href="/search/physics?searchtype=author&query=Chasapis%2C+A">A. Chasapis</a>, <a href="/search/physics?searchtype=author&query=Goldstein%2C+M+L">Melvyn L. Goldstein</a>, <a href="/search/physics?searchtype=author&query=Bale%2C+S+D">S. D. Bale</a>, <a href="/search/physics?searchtype=author&query=Bonnell%2C+J+W">J. W. Bonnell</a>, <a href="/search/physics?searchtype=author&query=de+Wit%2C+T+D">T. Dudok de Wit</a>, <a href="/search/physics?searchtype=author&query=Goetz%2C+K">K. Goetz</a>, <a href="/search/physics?searchtype=author&query=Harvey%2C+P+R">P. R. Harvey</a>, <a href="/search/physics?searchtype=author&query=MacDowall%2C+R+J">R. J. MacDowall</a>, <a href="/search/physics?searchtype=author&query=Malaspina%2C+D">D. Malaspina</a>, <a href="/search/physics?searchtype=author&query=Pulupa%2C+M">M. Pulupa</a>, <a href="/search/physics?searchtype=author&query=Kasper%2C+J+C">J. C. Kasper</a>, <a href="/search/physics?searchtype=author&query=Korreck%2C+K+E">K. E. Korreck</a>, <a href="/search/physics?searchtype=author&query=Case%2C+A+W">A. W. Case</a>, <a href="/search/physics?searchtype=author&query=Stevens%2C+M">M. Stevens</a>, <a href="/search/physics?searchtype=author&query=Whittlesey%2C+P">P. Whittlesey</a>, <a href="/search/physics?searchtype=author&query=Larson%2C+D">D. Larson</a>, <a href="/search/physics?searchtype=author&query=Livi%2C+R">R. Livi</a>, <a href="/search/physics?searchtype=author&query=Velli%2C+M">M. Velli</a>, <a href="/search/physics?searchtype=author&query=Raouafi%2C+N">N. Raouafi</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1912.05483v1-abstract-short" style="display: inline;"> The solar wind proton temperature at 1-au has been found to be correlated with small-scale intermittent magnetic structures, i.e., regions with enhanced temperature are associated with coherent structures such as current sheets. Using Parker Solar Probe data from the first encounter, we study this association using measurements of radial proton temperature, employing the Partial Variance of Increm… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1912.05483v1-abstract-full').style.display = 'inline'; document.getElementById('1912.05483v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1912.05483v1-abstract-full" style="display: none;"> The solar wind proton temperature at 1-au has been found to be correlated with small-scale intermittent magnetic structures, i.e., regions with enhanced temperature are associated with coherent structures such as current sheets. Using Parker Solar Probe data from the first encounter, we study this association using measurements of radial proton temperature, employing the Partial Variance of Increments (PVI) technique to identify intermittent magnetic structures. We observe that the probability density functions of high-PVI events have higher median temperatures than those with lower PVI, The regions in space where PVI peaks were also locations that had enhanced temperatures when compared with similar regions suggesting a heating mechanism in the young solar wind that is associated with intermittency developed by a nonlinear turbulent cascade.n the immediate vicinity. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1912.05483v1-abstract-full').style.display = 'none'; document.getElementById('1912.05483v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 11 December, 2019; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> December 2019. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">6 pages, 3 figures, part of ApJ special issue for PSP</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1912.03871">arXiv:1912.03871</a> <span> [<a href="https://arxiv.org/pdf/1912.03871">pdf</a>, <a href="https://arxiv.org/format/1912.03871">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Space Physics">physics.space-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Plasma Physics">physics.plasm-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.3847/1538-4365/ab74e0">10.3847/1538-4365/ab74e0 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Proton Temperature Anisotropy Variations in Inner Heliosphere Estimated with First Parker Solar Probe Observations </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Huang%2C+J">Jia Huang</a>, <a href="/search/physics?searchtype=author&query=Kasper%2C+J+C">Justin C. Kasper</a>, <a href="/search/physics?searchtype=author&query=Vech%2C+D">Daniel Vech</a>, <a href="/search/physics?searchtype=author&query=Klein%2C+K+G">Kristopher G. Klein</a>, <a href="/search/physics?searchtype=author&query=Stevens%2C+M+L">Michael L. Stevens</a>, <a href="/search/physics?searchtype=author&query=Martinovic%2C+M">Mihailo Martinovic</a>, <a href="/search/physics?searchtype=author&query=Alterman%2C+B+L">Benjamin L. Alterman</a>, <a href="/search/physics?searchtype=author&query=%C4%8Eurovcov%C3%A1%2C+T">Tereza 膸urovcov谩</a>, <a href="/search/physics?searchtype=author&query=Paulson%2C+K">Kristoff Paulson</a>, <a href="/search/physics?searchtype=author&query=Maruca%2C+B+A">Bennett A. Maruca</a>, <a href="/search/physics?searchtype=author&query=Qudsi%2C+R+A">Ramiz A. Qudsi</a>, <a href="/search/physics?searchtype=author&query=Case%2C+A+W">Anthony W. Case</a>, <a href="/search/physics?searchtype=author&query=Korreck%2C+K">Kelly Korreck</a>, <a href="/search/physics?searchtype=author&query=Jian%2C+L+K">Lan K. Jian</a>, <a href="/search/physics?searchtype=author&query=Velli%2C+M">Marco Velli</a>, <a href="/search/physics?searchtype=author&query=Lavraud%2C+B">Benoit Lavraud</a>, <a href="/search/physics?searchtype=author&query=Hegedus%2C+A+M">Alexander M. Hegedus</a>, <a href="/search/physics?searchtype=author&query=Bert%2C+C+M">C. M. Bert</a>, <a href="/search/physics?searchtype=author&query=Holmes%2C+J">J. Holmes</a>, <a href="/search/physics?searchtype=author&query=Bale%2C+S+D">Stuart D. Bale</a>, <a href="/search/physics?searchtype=author&query=Larson%2C+D+E">Davin E. Larson</a>, <a href="/search/physics?searchtype=author&query=Livi%2C+R">Roberto Livi</a>, <a href="/search/physics?searchtype=author&query=Whittlesey%2C+P">Phyllis Whittlesey</a>, <a href="/search/physics?searchtype=author&query=Pulupa%2C+M">Marc Pulupa</a>, <a href="/search/physics?searchtype=author&query=MacDowall%2C+R+J">Robert J. MacDowall</a> , et al. (5 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1912.03871v2-abstract-short" style="display: inline;"> We report proton temperature anisotropy variations in the inner heliosphere with Parker Solar Probe (PSP) observations. Using a linear fitting method, we derive proton temperature anisotropy with temperatures measured by the Solar Probe Cup (SPC) from the SWEAP instrument suite and magnetic field observations from the FIELDS instrument suite. The observed radial dependence of temperature variation… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1912.03871v2-abstract-full').style.display = 'inline'; document.getElementById('1912.03871v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1912.03871v2-abstract-full" style="display: none;"> We report proton temperature anisotropy variations in the inner heliosphere with Parker Solar Probe (PSP) observations. Using a linear fitting method, we derive proton temperature anisotropy with temperatures measured by the Solar Probe Cup (SPC) from the SWEAP instrument suite and magnetic field observations from the FIELDS instrument suite. The observed radial dependence of temperature variations in the fast solar wind implies stronger perpendicular heating and parallel cooling than previous results from Helios measurements made at larger radial distances. The anti-correlation between proton temperature anisotropy and parallel plasma beta is retained in fast solar wind. However, the temperature anisotropies of the slow solar wind seem to be well constrained by the mirror and parallel firehose instabilities. The perpendicular heating of the slow solar wind inside 0.24 AU may contribute to its same trend up against mirror instability thresholds as fast solar wind. These results suggest that we may see stronger anisotropy heating than expected in inner heliosphere. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1912.03871v2-abstract-full').style.display = 'none'; document.getElementById('1912.03871v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 8 February, 2020; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 9 December, 2019; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> December 2019. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">Submit to ApJ special issue for Parker Solar Probe first results</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1912.03777">arXiv:1912.03777</a> <span> [<a href="https://arxiv.org/pdf/1912.03777">pdf</a>, <a href="https://arxiv.org/format/1912.03777">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Solar and Stellar Astrophysics">astro-ph.SR</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Space Physics">physics.space-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.3847/1538-4365/ab4fef">10.3847/1538-4365/ab4fef <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> The role of Alfv茅n wave dynamics on the large scale properties of the solar wind: comparing an MHD simulation with PSP E1 data </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=R%C3%A9ville%2C+V">Victor R茅ville</a>, <a href="/search/physics?searchtype=author&query=Velli%2C+M">Marco Velli</a>, <a href="/search/physics?searchtype=author&query=Panasenco%2C+O">Olga Panasenco</a>, <a href="/search/physics?searchtype=author&query=Tenerani%2C+A">Anna Tenerani</a>, <a href="/search/physics?searchtype=author&query=Shi%2C+C">Chen Shi</a>, <a href="/search/physics?searchtype=author&query=Badman%2C+S+T">Samuel T. Badman</a>, <a href="/search/physics?searchtype=author&query=Bale%2C+S+D">Stuart D. Bale</a>, <a href="/search/physics?searchtype=author&query=Kasper%2C+J+C">J. C. Kasper</a>, <a href="/search/physics?searchtype=author&query=Stevens%2C+M+L">Michael L. Stevens</a>, <a href="/search/physics?searchtype=author&query=Korreck%2C+K+E">Kelly E. Korreck</a>, <a href="/search/physics?searchtype=author&query=Bonnell%2C+J+W">J. W. Bonnell</a>, <a href="/search/physics?searchtype=author&query=Case%2C+A+W">Anthony W. Case</a>, <a href="/search/physics?searchtype=author&query=de+Wit%2C+T+D">Thierry Dudok de Wit</a>, <a href="/search/physics?searchtype=author&query=Goetz%2C+K">Keith Goetz</a>, <a href="/search/physics?searchtype=author&query=Harvey%2C+P+R">Peter R. Harvey</a>, <a href="/search/physics?searchtype=author&query=Larson%2C+D+E">Davin E. Larson</a>, <a href="/search/physics?searchtype=author&query=Livi%2C+R">Roberto Livi</a>, <a href="/search/physics?searchtype=author&query=Malaspina%2C+D+M">David M. Malaspina</a>, <a href="/search/physics?searchtype=author&query=MacDowall%2C+R+J">Robert J. MacDowall</a>, <a href="/search/physics?searchtype=author&query=Pulupa%2C+M">Marc Pulupa</a>, <a href="/search/physics?searchtype=author&query=Whittlesey%2C+P+L">Phyllis L. Whittlesey</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1912.03777v2-abstract-short" style="display: inline;"> During Parker Solar Probe's first orbit, the solar wind plasma has been observed in situ closer than ever before, the perihelion on November 6th 2018 revealing a flow that is constantly permeated by large amplitude Alfv茅nic fluctuations. These include radial magnetic field reversals, or switchbacks, that seem to be a persistent feature of the young solar wind. The measurements also reveal a very s… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1912.03777v2-abstract-full').style.display = 'inline'; document.getElementById('1912.03777v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1912.03777v2-abstract-full" style="display: none;"> During Parker Solar Probe's first orbit, the solar wind plasma has been observed in situ closer than ever before, the perihelion on November 6th 2018 revealing a flow that is constantly permeated by large amplitude Alfv茅nic fluctuations. These include radial magnetic field reversals, or switchbacks, that seem to be a persistent feature of the young solar wind. The measurements also reveal a very strong, unexpected, azimuthal velocity component. In this work, we numerically model the solar corona during this first encounter, solving the MHD equations and accounting for Alfv茅n wave transport and dissipation. We find that the large scale plasma parameters are well reproduced, allowing the computation of the solar wind sources at Probe with confidence. We try to understand the dynamical nature of the solar wind to explain both the amplitude of the observed radial magnetic field and of the azimuthal velocities. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1912.03777v2-abstract-full').style.display = 'none'; document.getElementById('1912.03777v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 10 February, 2022; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 8 December, 2019; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> December 2019. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">Accepted Erratum includeded as an appendix. Updated references. 17 pages, 9 figures total</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1912.03424">arXiv:1912.03424</a> <span> [<a href="https://arxiv.org/pdf/1912.03424">pdf</a>, <a href="https://arxiv.org/format/1912.03424">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Space Physics">physics.space-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Solar and Stellar Astrophysics">astro-ph.SR</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Plasma Physics">physics.plasm-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.3847/1538-4365/ab6220">10.3847/1538-4365/ab6220 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Observations of Energetic-Particle Population Enhancements along Intermittent Structures near the Sun from Parker Solar Probe </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Bandyopadhyay%2C+R">Riddhi Bandyopadhyay</a>, <a href="/search/physics?searchtype=author&query=Matthaeus%2C+W+H">W. H. Matthaeus</a>, <a href="/search/physics?searchtype=author&query=Parashar%2C+T+N">T. N. Parashar</a>, <a href="/search/physics?searchtype=author&query=Chhiber%2C+R">R. Chhiber</a>, <a href="/search/physics?searchtype=author&query=Ruffolo%2C+D">D. Ruffolo</a>, <a href="/search/physics?searchtype=author&query=Goldstein%2C+M+L">M. L. Goldstein</a>, <a href="/search/physics?searchtype=author&query=Maruca%2C+B+A">B. A. Maruca</a>, <a href="/search/physics?searchtype=author&query=Chasapis%2C+A">A. Chasapis</a>, <a href="/search/physics?searchtype=author&query=Qudsi%2C+R">R. Qudsi</a>, <a href="/search/physics?searchtype=author&query=McComas%2C+D+J">D. J. McComas</a>, <a href="/search/physics?searchtype=author&query=Christian%2C+E+R">E. R. Christian</a>, <a href="/search/physics?searchtype=author&query=Szalay%2C+J+R">J. R. Szalay</a>, <a href="/search/physics?searchtype=author&query=Joyce%2C+C+J">C. J. Joyce</a>, <a href="/search/physics?searchtype=author&query=Giacalone%2C+J">J. Giacalone</a>, <a href="/search/physics?searchtype=author&query=Schwadron%2C+N+A">N. A. Schwadron</a>, <a href="/search/physics?searchtype=author&query=Mitchell%2C+D+G">D. G. Mitchell</a>, <a href="/search/physics?searchtype=author&query=Hill%2C+M+E">M. E. Hill</a>, <a href="/search/physics?searchtype=author&query=Wiedenbeck%2C+M+E">M. E. Wiedenbeck</a>, <a href="/search/physics?searchtype=author&query=McNutt%2C+R+L">R. L. McNutt Jr.</a>, <a href="/search/physics?searchtype=author&query=Desai%2C+M+I">M. I. Desai</a>, <a href="/search/physics?searchtype=author&query=Bale%2C+S+D">Stuart D. Bale</a>, <a href="/search/physics?searchtype=author&query=Bonnell%2C+J+W">J. W. Bonnell</a>, <a href="/search/physics?searchtype=author&query=de+Wit%2C+T+D">Thierry Dudok de Wit</a>, <a href="/search/physics?searchtype=author&query=Goetz%2C+K">Keith Goetz</a>, <a href="/search/physics?searchtype=author&query=Harvey%2C+P+R">Peter R. Harvey</a> , et al. (9 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1912.03424v2-abstract-short" style="display: inline;"> Observations at 1 au have confirmed that enhancements in measured energetic particle fluxes are statistically associated with "rough" magnetic fields, i.e., fields having atypically large spatial derivatives or increments, as measured by the Partial Variance of Increments (PVI) method. One way to interpret this observation is as an association of the energetic particles with trapping or channeling… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1912.03424v2-abstract-full').style.display = 'inline'; document.getElementById('1912.03424v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1912.03424v2-abstract-full" style="display: none;"> Observations at 1 au have confirmed that enhancements in measured energetic particle fluxes are statistically associated with "rough" magnetic fields, i.e., fields having atypically large spatial derivatives or increments, as measured by the Partial Variance of Increments (PVI) method. One way to interpret this observation is as an association of the energetic particles with trapping or channeling within magnetic flux tubes, possibly near their boundaries. However, it remains unclear whether this association is a transport or local effect; i.e., the particles might have been energized at a distant location, perhaps by shocks or reconnection, or they might experience local energization or re-acceleration. The Parker Solar Probe (PSP), even in its first two orbits, offers a unique opportunity to study this statistical correlation closer to the corona. As a first step, we analyze the separate correlation properties of the energetic particles measured by the \isois instruments during the first solar encounter. The distribution of time intervals between a specific type of event, i.e., the waiting time, can indicate the nature of the underlying process. We find that the \isois observations show a power-law distribution of waiting times, indicating a correlated (non-Poisson) distribution. Analysis of low-energy \isois data suggests that the results are consistent with the 1 au studies, although we find hints of some unexpected behavior. A more complete understanding of these statistical distributions will provide valuable insights into the origin and propagation of solar energetic particles, a picture that should become clear with future PSP orbits. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1912.03424v2-abstract-full').style.display = 'none'; document.getElementById('1912.03424v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 19 December, 2019; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 6 December, 2019; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> December 2019. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">Accepted for publication in The Astrophysical Journal Supplement, PSP special issue</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1912.03384">arXiv:1912.03384</a> <span> [<a href="https://arxiv.org/pdf/1912.03384">pdf</a>, <a href="https://arxiv.org/ps/1912.03384">ps</a>, <a href="https://arxiv.org/format/1912.03384">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Solar and Stellar Astrophysics">astro-ph.SR</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Space Physics">physics.space-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.3847/1538-4365/ab5712">10.3847/1538-4365/ab5712 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Observations of the 2019 April 4 Solar Energetic Particle Event at the Parker Solar Probe </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Leske%2C+R+A">R. A. Leske</a>, <a href="/search/physics?searchtype=author&query=Christian%2C+E+R">E. R. Christian</a>, <a href="/search/physics?searchtype=author&query=Cohen%2C+C+M+S">C. M. S. Cohen</a>, <a href="/search/physics?searchtype=author&query=Cummings%2C+A+C">A. C. Cummings</a>, <a href="/search/physics?searchtype=author&query=Davis%2C+A+J">A. J. Davis</a>, <a href="/search/physics?searchtype=author&query=Desai%2C+M+I">M. I. Desai</a>, <a href="/search/physics?searchtype=author&query=Giacalone%2C+J">J. Giacalone</a>, <a href="/search/physics?searchtype=author&query=Hill%2C+M+E">M. E. Hill</a>, <a href="/search/physics?searchtype=author&query=Joyce%2C+C+J">C. J. Joyce</a>, <a href="/search/physics?searchtype=author&query=Krimigis%2C+S+M">S. M. Krimigis</a>, <a href="/search/physics?searchtype=author&query=Labrador%2C+A+W">A. W. Labrador</a>, <a href="/search/physics?searchtype=author&query=Malandraki%2C+O">O. Malandraki</a>, <a href="/search/physics?searchtype=author&query=Matthaeus%2C+W+H">W. H. Matthaeus</a>, <a href="/search/physics?searchtype=author&query=McComas%2C+D+J">D. J. McComas</a>, <a href="/search/physics?searchtype=author&query=McNutt%2C+R+L">R. L. McNutt Jr.</a>, <a href="/search/physics?searchtype=author&query=Mewaldt%2C+R+A">R. A. Mewaldt</a>, <a href="/search/physics?searchtype=author&query=Mitchell%2C+D+G">D. G. Mitchell</a>, <a href="/search/physics?searchtype=author&query=Posner%2C+A">A. Posner</a>, <a href="/search/physics?searchtype=author&query=Rankin%2C+J+S">J. S. Rankin</a>, <a href="/search/physics?searchtype=author&query=Roelof%2C+E+C">E. C. Roelof</a>, <a href="/search/physics?searchtype=author&query=Schwadron%2C+N+A">N. A. Schwadron</a>, <a href="/search/physics?searchtype=author&query=Stone%2C+E+C">E. C. Stone</a>, <a href="/search/physics?searchtype=author&query=Szalay%2C+J+R">J. R. Szalay</a>, <a href="/search/physics?searchtype=author&query=Wiedenbeck%2C+M+E">M. E. Wiedenbeck</a>, <a href="/search/physics?searchtype=author&query=Vourlidas%2C+A">A. Vourlidas</a> , et al. (11 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1912.03384v1-abstract-short" style="display: inline;"> A solar energetic particle event was detected by the Integrated Science Investigation of the Sun (ISOIS) instrument suite on Parker Solar Probe (PSP) on 2019 April 4 when the spacecraft was inside of 0.17 au and less than 1 day before its second perihelion, providing an opportunity to study solar particle acceleration and transport unprecedentedly close to the source. The event was very small, wit… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1912.03384v1-abstract-full').style.display = 'inline'; document.getElementById('1912.03384v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1912.03384v1-abstract-full" style="display: none;"> A solar energetic particle event was detected by the Integrated Science Investigation of the Sun (ISOIS) instrument suite on Parker Solar Probe (PSP) on 2019 April 4 when the spacecraft was inside of 0.17 au and less than 1 day before its second perihelion, providing an opportunity to study solar particle acceleration and transport unprecedentedly close to the source. The event was very small, with peak 1 MeV proton intensities of ~0.3 particles (cm^2 sr s MeV)^-1, and was undetectable above background levels at energies above 10 MeV or in particle detectors at 1 au. It was strongly anisotropic, with intensities flowing outward from the Sun up to 30 times greater than those flowing inward persisting throughout the event. Temporal association between particle increases and small brightness surges in the extreme-ultraviolet observed by the Solar TErrestrial RElations Observatory, which were also accompanied by type III radio emission seen by the Electromagnetic Fields Investigation on PSP, indicates that the source of this event was an active region nearly 80 degrees east of the nominal PSP magnetic footpoint. This suggests that the field lines expanded over a wide longitudinal range between the active region in the photosphere and the corona. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1912.03384v1-abstract-full').style.display = 'none'; document.getElementById('1912.03384v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 6 December, 2019; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> December 2019. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1912.03371">arXiv:1912.03371</a> <span> [<a href="https://arxiv.org/pdf/1912.03371">pdf</a>, <a href="https://arxiv.org/format/1912.03371">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Solar and Stellar Astrophysics">astro-ph.SR</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Space Physics">physics.space-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.3847/1538-4365/ab5dc0">10.3847/1538-4365/ab5dc0 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Statistics and Polarization of Type III Radio Bursts Observed in the Inner Heliosphere </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Pulupa%2C+M">Marc Pulupa</a>, <a href="/search/physics?searchtype=author&query=Bale%2C+S+D">Stuart D. Bale</a>, <a href="/search/physics?searchtype=author&query=Badman%2C+S+T">Samuel T. Badman</a>, <a href="/search/physics?searchtype=author&query=Bonnell%2C+J+W">John W. Bonnell</a>, <a href="/search/physics?searchtype=author&query=Case%2C+A+W">Anthony W. Case</a>, <a href="/search/physics?searchtype=author&query=de+Wit%2C+T+D">Thierry Dudok de Wit</a>, <a href="/search/physics?searchtype=author&query=Goetz%2C+K">Keith Goetz</a>, <a href="/search/physics?searchtype=author&query=Harvey%2C+P+R">Peter R. Harvey</a>, <a href="/search/physics?searchtype=author&query=Hegedus%2C+A+M">Alexander M. Hegedus</a>, <a href="/search/physics?searchtype=author&query=Kasper%2C+J+C">Justin C. Kasper</a>, <a href="/search/physics?searchtype=author&query=Korreck%2C+K+E">Kelly E. Korreck</a>, <a href="/search/physics?searchtype=author&query=Krasnoselskikh%2C+V">Vladimir Krasnoselskikh</a>, <a href="/search/physics?searchtype=author&query=Larson%2C+D">Davin Larson</a>, <a href="/search/physics?searchtype=author&query=Lecacheux%2C+A">Alain Lecacheux</a>, <a href="/search/physics?searchtype=author&query=Livi%2C+R">Roberto Livi</a>, <a href="/search/physics?searchtype=author&query=MacDowall%2C+R+J">Robert J. MacDowall</a>, <a href="/search/physics?searchtype=author&query=Maksimovic%2C+M">Milan Maksimovic</a>, <a href="/search/physics?searchtype=author&query=Malaspina%2C+D+M">David M. Malaspina</a>, <a href="/search/physics?searchtype=author&query=Oliveros%2C+J+C+M">Juan Carlos Mart铆nez Oliveros</a>, <a href="/search/physics?searchtype=author&query=Meyer-Vernet%2C+N">Nicole Meyer-Vernet</a>, <a href="/search/physics?searchtype=author&query=Moncuquet%2C+M">Michel Moncuquet</a>, <a href="/search/physics?searchtype=author&query=Stevens%2C+M">Michael Stevens</a>, <a href="/search/physics?searchtype=author&query=Whittlesey%2C+P">Phyllis Whittlesey</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1912.03371v1-abstract-short" style="display: inline;"> We present initial results from the Radio Frequency Spectrometer (RFS), the high frequency component of the FIELDS experiment on the Parker Solar Probe (PSP). During the first PSP solar encounter (2018 November), only a few small radio bursts were observed. During the second encounter (2019 April), copious Type III radio bursts occurred, including intervals of radio storms where bursts occurred co… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1912.03371v1-abstract-full').style.display = 'inline'; document.getElementById('1912.03371v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1912.03371v1-abstract-full" style="display: none;"> We present initial results from the Radio Frequency Spectrometer (RFS), the high frequency component of the FIELDS experiment on the Parker Solar Probe (PSP). During the first PSP solar encounter (2018 November), only a few small radio bursts were observed. During the second encounter (2019 April), copious Type III radio bursts occurred, including intervals of radio storms where bursts occurred continuously. In this paper, we present initial observations of the characteristics of Type III radio bursts in the inner heliosphere, calculating occurrence rates, amplitude distributions, and spectral properties of the observed bursts. We also report observations of several bursts during the second encounter which display circular polarization in the right hand polarized sense, with a degree of polarization of 0.15-0.38 in the range from 8-12 MHz. The degree of polarization can be explained either by depolarization of initially 100% polarized $o$-mode emission, or by direct generation of emission in the $o$ and $x$-mode simultaneously. Direct in situ observations in future PSP encounters could provide data which can distinguish these mechanisms. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1912.03371v1-abstract-full').style.display = 'none'; document.getElementById('1912.03371v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 6 December, 2019; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> December 2019. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">12 pages, 7 figures, to be published in ApJS</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1912.03240">arXiv:1912.03240</a> <span> [<a href="https://arxiv.org/pdf/1912.03240">pdf</a>, <a href="https://arxiv.org/format/1912.03240">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Space Physics">physics.space-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Solar and Stellar Astrophysics">astro-ph.SR</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.3847/1538-4365/ab53e1">10.3847/1538-4365/ab53e1 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Magnetic field kinks and folds in the solar wind </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Tenerani%2C+A">Anna Tenerani</a>, <a href="/search/physics?searchtype=author&query=Velli%2C+M">Marco Velli</a>, <a href="/search/physics?searchtype=author&query=Matteini%2C+L">Lorenzo Matteini</a>, <a href="/search/physics?searchtype=author&query=R%C3%A9ville%2C+V">Victor R茅ville</a>, <a href="/search/physics?searchtype=author&query=Shi%2C+C">Chen Shi</a>, <a href="/search/physics?searchtype=author&query=Bale%2C+S+D">Stuart D. Bale</a>, <a href="/search/physics?searchtype=author&query=Kasper%2C+J">Justin Kasper</a>, <a href="/search/physics?searchtype=author&query=Bonnell%2C+J+W">J. W. Bonnell</a>, <a href="/search/physics?searchtype=author&query=Case%2C+A+W">Anthony W. Case</a>, <a href="/search/physics?searchtype=author&query=de+Wit%2C+T+D">Thierry Dudok de Wit</a>, <a href="/search/physics?searchtype=author&query=Goetz%2C+K">Keith Goetz</a>, <a href="/search/physics?searchtype=author&query=Harvey%2C+P+R">Peter R. Harvey</a>, <a href="/search/physics?searchtype=author&query=Klein%2C+K+G">Kristopher G. Klein</a>, <a href="/search/physics?searchtype=author&query=Korreck%2C+K">Kelly Korreck</a>, <a href="/search/physics?searchtype=author&query=Larson%2C+D">Davin Larson</a>, <a href="/search/physics?searchtype=author&query=Livi%2C+R">Roberto Livi</a>, <a href="/search/physics?searchtype=author&query=MacDowall%2C+R+J">Robert J. MacDowall</a>, <a href="/search/physics?searchtype=author&query=Malaspina%2C+D+M">David M. Malaspina</a>, <a href="/search/physics?searchtype=author&query=Pulupa%2C+M">Marc Pulupa</a>, <a href="/search/physics?searchtype=author&query=Stevens%2C+M">Michael Stevens</a>, <a href="/search/physics?searchtype=author&query=Whittlesey%2C+P">Phyllis Whittlesey</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1912.03240v1-abstract-short" style="display: inline;"> Parker Solar Probe (PSP) observations during its first encounter at 35.7 $R_\odot$ have shown the presence of magnetic field lines which are strongly perturbed to the point that they produce local inversions of the radial magnetic field, known as switchbacks. Their counterparts in the solar wind velocity field are local enhancements in the radial speed, or jets, displaying (in all components) the… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1912.03240v1-abstract-full').style.display = 'inline'; document.getElementById('1912.03240v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1912.03240v1-abstract-full" style="display: none;"> Parker Solar Probe (PSP) observations during its first encounter at 35.7 $R_\odot$ have shown the presence of magnetic field lines which are strongly perturbed to the point that they produce local inversions of the radial magnetic field, known as switchbacks. Their counterparts in the solar wind velocity field are local enhancements in the radial speed, or jets, displaying (in all components) the velocity-magnetic field correlation typical of large amplitude Alfv茅n waves propagating away from the Sun. Switchbacks and radial jets have previously been observed over a wide range of heliocentric distances by Helios, WIND and Ulysses, although they were prevalent in significantly faster streams than seen at PSP. Here we study via numerical MHD simulations the evolution of such large amplitude Alfv茅nic fluctuations by including, in agreement with observations, both a radial magnetic field inversion and an initially constant total magnetic pressure. Despite the extremely large excursion of magnetic and velocity fields, switchbacks are seen to persist for up to hundreds of Alfv茅n crossing times before eventually decaying due to the parametric decay instability. Our results suggest that such switchback/jet configurations might indeed originate in the lower corona and survive out to PSP distances, provided the background solar wind is sufficiently calm, in the sense of not being pervaded by strong density fluctuations or other gradients, such as stream or magnetic field shears, that might destabilize or destroy them over shorter timescales. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1912.03240v1-abstract-full').style.display = 'none'; document.getElementById('1912.03240v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 6 December, 2019; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> December 2019. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">Accepted for publication on APJ PSP special issue</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1912.02959">arXiv:1912.02959</a> <span> [<a href="https://arxiv.org/pdf/1912.02959">pdf</a>, <a href="https://arxiv.org/format/1912.02959">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Space Physics">physics.space-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Solar and Stellar Astrophysics">astro-ph.SR</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Plasma Physics">physics.plasm-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.3847/1538-4365/ab5dae">10.3847/1538-4365/ab5dae <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Enhanced Energy Transfer Rate in Solar Wind Turbulence Observed near the Sun from Parker Solar Probe </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Bandyopadhyay%2C+R">Riddhi Bandyopadhyay</a>, <a href="/search/physics?searchtype=author&query=Goldstein%2C+M+L">M. L. Goldstein</a>, <a href="/search/physics?searchtype=author&query=Maruca%2C+B+A">B. A. Maruca</a>, <a href="/search/physics?searchtype=author&query=Matthaeus%2C+W+H">W. H. Matthaeus</a>, <a href="/search/physics?searchtype=author&query=Parashar%2C+T+N">T. N. Parashar</a>, <a href="/search/physics?searchtype=author&query=Ruffolo%2C+D">D. Ruffolo</a>, <a href="/search/physics?searchtype=author&query=Chhiber%2C+R">R. Chhiber</a>, <a href="/search/physics?searchtype=author&query=Usmanov%2C+A">A. Usmanov</a>, <a href="/search/physics?searchtype=author&query=Chasapis%2C+A">A. Chasapis</a>, <a href="/search/physics?searchtype=author&query=Qudsi%2C+R">R. Qudsi</a>, <a href="/search/physics?searchtype=author&query=Bale%2C+S+D">Stuart D. Bale</a>, <a href="/search/physics?searchtype=author&query=Bonnell%2C+J+W">J. W. Bonnell</a>, <a href="/search/physics?searchtype=author&query=de+Wit%2C+T+D">Thierry Dudok de Wit</a>, <a href="/search/physics?searchtype=author&query=Goetz%2C+K">Keith Goetz</a>, <a href="/search/physics?searchtype=author&query=Harvey%2C+P+R">Peter R. Harvey</a>, <a href="/search/physics?searchtype=author&query=MacDowall%2C+R+J">Robert J. MacDowall</a>, <a href="/search/physics?searchtype=author&query=Malaspina%2C+D+M">David M. Malaspina</a>, <a href="/search/physics?searchtype=author&query=Pulupa%2C+M">Marc Pulupa</a>, <a href="/search/physics?searchtype=author&query=Kasper%2C+J+C">J. C. Kasper</a>, <a href="/search/physics?searchtype=author&query=Korreck%2C+K+E">K. E. Korreck</a>, <a href="/search/physics?searchtype=author&query=Case%2C+A+W">A. W. Case</a>, <a href="/search/physics?searchtype=author&query=Stevens%2C+M">M. Stevens</a>, <a href="/search/physics?searchtype=author&query=Whittlesey%2C+P">P. Whittlesey</a>, <a href="/search/physics?searchtype=author&query=Larson%2C+D">D. Larson</a>, <a href="/search/physics?searchtype=author&query=Livi%2C+R">R. Livi</a> , et al. (3 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1912.02959v2-abstract-short" style="display: inline;"> Direct evidence of an inertial-range turbulent energy cascade has been provided by spacecraft observations in heliospheric plasmas. In the solar wind, the average value of the derived heating rate near 1 au is $\sim 10^{3}\, \mathrm{J\,kg^{-1}\,s^{-1}}$, an amount sufficient to account for observed departures from adiabatic expansion. Parker Solar Probe (PSP), even during its first solar encounter… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1912.02959v2-abstract-full').style.display = 'inline'; document.getElementById('1912.02959v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1912.02959v2-abstract-full" style="display: none;"> Direct evidence of an inertial-range turbulent energy cascade has been provided by spacecraft observations in heliospheric plasmas. In the solar wind, the average value of the derived heating rate near 1 au is $\sim 10^{3}\, \mathrm{J\,kg^{-1}\,s^{-1}}$, an amount sufficient to account for observed departures from adiabatic expansion. Parker Solar Probe (PSP), even during its first solar encounter, offers the first opportunity to compute, in a similar fashion, a fluid-scale energy decay rate, much closer to the solar corona than any prior in-situ observations. Using the Politano-Pouquet third-order law and the von K谩rm谩n decay law, we estimate the fluid-range energy transfer rate in the inner heliosphere, at heliocentric distance $R$ ranging from $54\,R_{\odot}$ (0.25 au) to $36\,R_{\odot}$ (0.17 au). The energy transfer rate obtained near the first perihelion is about 100 times higher than the average value at 1 au. This dramatic increase in the heating rate is unprecedented in previous solar wind observations, including those from Helios, and the values are close to those obtained in the shocked plasma inside the terrestrial magnetosheath. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1912.02959v2-abstract-full').style.display = 'none'; document.getElementById('1912.02959v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 17 December, 2019; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 5 December, 2019; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> December 2019. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">Accepted for publication in The Astrophysical Journal Supplement, PSP special issue</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1912.02653">arXiv:1912.02653</a> <span> [<a href="https://arxiv.org/pdf/1912.02653">pdf</a>, <a href="https://arxiv.org/format/1912.02653">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Solar and Stellar Astrophysics">astro-ph.SR</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Plasma Physics">physics.plasm-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.3847/1538-4365/ab527f">10.3847/1538-4365/ab527f <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> The Enhancement of Proton Stochastic Heating in the near-Sun Solar Wind </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Martinovi%C4%87%2C+M+M">Mihailo M. Martinovi膰</a>, <a href="/search/physics?searchtype=author&query=Klein%2C+K+G">Kristopher G. Klein</a>, <a href="/search/physics?searchtype=author&query=Kasper%2C+J+C">Justin C. Kasper</a>, <a href="/search/physics?searchtype=author&query=Case%2C+A+W">Anthony W. Case</a>, <a href="/search/physics?searchtype=author&query=Korreck%2C+K+E">Kelly E. Korreck</a>, <a href="/search/physics?searchtype=author&query=Larson%2C+D">Davin Larson</a>, <a href="/search/physics?searchtype=author&query=Livi%2C+R">Roberto Livi</a>, <a href="/search/physics?searchtype=author&query=Stevens%2C+M">Michael Stevens</a>, <a href="/search/physics?searchtype=author&query=Whittlesey%2C+P">Phyllis Whittlesey</a>, <a href="/search/physics?searchtype=author&query=Chandran%2C+B+D+G">Benjamin D. G. Chandran</a>, <a href="/search/physics?searchtype=author&query=Alterman%2C+B+L">Ben L. Alterman</a>, <a href="/search/physics?searchtype=author&query=Huang%2C+J">Jia Huang</a>, <a href="/search/physics?searchtype=author&query=Chen%2C+C+H+K">Christopher H. K. Chen</a>, <a href="/search/physics?searchtype=author&query=Bale%2C+S+D">Stuart D. Bale</a>, <a href="/search/physics?searchtype=author&query=Pulupa%2C+M">Marc Pulupa</a>, <a href="/search/physics?searchtype=author&query=Malaspina%2C+D+M">David M. Malaspina</a>, <a href="/search/physics?searchtype=author&query=Bonnell%2C+J+W">John W. Bonnell</a>, <a href="/search/physics?searchtype=author&query=Harvey%2C+P+R">Peter R. Harvey</a>, <a href="/search/physics?searchtype=author&query=Goetz%2C+K">Keith Goetz</a>, <a href="/search/physics?searchtype=author&query=de+Wit%2C+T+D">Thierry Dudok de Wit</a>, <a href="/search/physics?searchtype=author&query=MacDowall%2C+R+J">Robert J. MacDowall</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1912.02653v1-abstract-short" style="display: inline;"> Stochastic heating is a non-linear heating mechanism driven by the violation of magnetic moment invariance due to large-amplitude turbulent fluctuations producing diffusion of ions towards higher kinetic energies in the direction perpendicular to the magnetic field. It is frequently invoked as a mechanism responsible for the heating of ions in the solar wind. Here, we quantify for the first time t… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1912.02653v1-abstract-full').style.display = 'inline'; document.getElementById('1912.02653v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1912.02653v1-abstract-full" style="display: none;"> Stochastic heating is a non-linear heating mechanism driven by the violation of magnetic moment invariance due to large-amplitude turbulent fluctuations producing diffusion of ions towards higher kinetic energies in the direction perpendicular to the magnetic field. It is frequently invoked as a mechanism responsible for the heating of ions in the solar wind. Here, we quantify for the first time the proton stochastic heating rate $Q_\perp$ at radial distances from the Sun as close as $0.16$ au, using measurements from the first two Parker Solar Probe encounters. Our results for both the amplitude and radial trend of the heating rate, $Q_\perp \propto r^{-2.5}$, agree with previous results based on the Helios data set at heliocentric distances from 0.3 to 0.9 au. Also in agreement with previous results, $Q_\perp$ is significantly larger in the fast solar wind than in the slow solar wind. We identify the tendency in fast solar wind for cuts of the core proton velocity distribution transverse to the magnetic field to exhibit a flat-top shape. The observed distribution agrees with previous theoretical predictions for fast solar wind where stochastic heating is the dominant heating mechanism. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1912.02653v1-abstract-full').style.display = 'none'; document.getElementById('1912.02653v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 5 December, 2019; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> December 2019. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1912.02581">arXiv:1912.02581</a> <span> [<a href="https://arxiv.org/pdf/1912.02581">pdf</a>, <a href="https://arxiv.org/format/1912.02581">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Instrumentation and Methods for Astrophysics">astro-ph.IM</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Solar and Stellar Astrophysics">astro-ph.SR</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Plasma Physics">physics.plasm-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Space Physics">physics.space-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.3847/1538-4365/ab5a7b">10.3847/1538-4365/ab5a7b <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> The Solar Probe Cup on Parker Solar Probe </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Case%2C+A+W">Anthony W. Case</a>, <a href="/search/physics?searchtype=author&query=Kasper%2C+J+C">Justin C. Kasper</a>, <a href="/search/physics?searchtype=author&query=Stevens%2C+M+L">Michael L. Stevens</a>, <a href="/search/physics?searchtype=author&query=Korreck%2C+K+E">Kelly E. Korreck</a>, <a href="/search/physics?searchtype=author&query=Paulson%2C+K">Kristoff Paulson</a>, <a href="/search/physics?searchtype=author&query=Daigneau%2C+P">Peter Daigneau</a>, <a href="/search/physics?searchtype=author&query=Caldwell%2C+D">Dave Caldwell</a>, <a href="/search/physics?searchtype=author&query=Freeman%2C+M">Mark Freeman</a>, <a href="/search/physics?searchtype=author&query=Henry%2C+T">Thayne Henry</a>, <a href="/search/physics?searchtype=author&query=Klingensmith%2C+B">Brianna Klingensmith</a>, <a href="/search/physics?searchtype=author&query=Robinson%2C+M">Miles Robinson</a>, <a href="/search/physics?searchtype=author&query=Berg%2C+P">Peter Berg</a>, <a href="/search/physics?searchtype=author&query=Tiu%2C+C">Chris Tiu</a>, <a href="/search/physics?searchtype=author&query=Wright%2C+K+H">Kenneth H. Wright Jr.</a>, <a href="/search/physics?searchtype=author&query=Curtis%2C+D">David Curtis</a>, <a href="/search/physics?searchtype=author&query=Ludlam%2C+M">Michael Ludlam</a>, <a href="/search/physics?searchtype=author&query=Larson%2C+D">Davin Larson</a>, <a href="/search/physics?searchtype=author&query=Whittlesey%2C+P">Phyllis Whittlesey</a>, <a href="/search/physics?searchtype=author&query=Livi%2C+R">Roberto Livi</a>, <a href="/search/physics?searchtype=author&query=Klein%2C+K+G">Kristopher G. Klein</a>, <a href="/search/physics?searchtype=author&query=Martinovi%C4%87%2C+M+M">Mihailo M. Martinovi膰</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1912.02581v1-abstract-short" style="display: inline;"> The Solar Probe Cup (SPC) is a Faraday Cup instrument onboard NASA's Parker Solar Probe (PSP) spacecraft designed to make rapid measurements of thermal coronal and solar wind plasma. The spacecraft is in a heliocentric orbit that takes it closer to the Sun than any previous spacecraft, allowing measurements to be made where the coronal and solar wind plasma is being heated and accelerated. The SPC… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1912.02581v1-abstract-full').style.display = 'inline'; document.getElementById('1912.02581v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1912.02581v1-abstract-full" style="display: none;"> The Solar Probe Cup (SPC) is a Faraday Cup instrument onboard NASA's Parker Solar Probe (PSP) spacecraft designed to make rapid measurements of thermal coronal and solar wind plasma. The spacecraft is in a heliocentric orbit that takes it closer to the Sun than any previous spacecraft, allowing measurements to be made where the coronal and solar wind plasma is being heated and accelerated. The SPC instrument was designed to be pointed directly at the Sun at all times, allowing the solar wind (which is flowing primarily radially away from the Sun) to be measured throughout the orbit. The instrument is capable of measuring solar wind ions with an energy/charge between 100 V and 6000 V (protons with speeds from $139-1072~km~s^{-1})$. It also measures electrons with an energy between 100 V and 1500 V. SPC has been designed to have a wide dynamic range that is capable of measuring protons and alpha particles at the closest perihelion (9.86 solar radii from the center of the Sun) and out to 0.25 AU. Initial observations from the first orbit of PSP indicate that the instrument is functioning well. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1912.02581v1-abstract-full').style.display = 'none'; document.getElementById('1912.02581v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 5 December, 2019; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> December 2019. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1912.02397">arXiv:1912.02397</a> <span> [<a href="https://arxiv.org/pdf/1912.02397">pdf</a>, <a href="https://arxiv.org/format/1912.02397">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Space Physics">physics.space-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Solar and Stellar Astrophysics">astro-ph.SR</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.3847/1538-4365/ab58c9">10.3847/1538-4365/ab58c9 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Predicting the Solar Wind at Parker Solar Probe Using an Empirically Driven MHD Model </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Kim%2C+T+K">T. K. Kim</a>, <a href="/search/physics?searchtype=author&query=Pogorelov%2C+N+V">N. V. Pogorelov</a>, <a href="/search/physics?searchtype=author&query=Arge%2C+C+N">C. N. Arge</a>, <a href="/search/physics?searchtype=author&query=Henney%2C+C+J">C. J. Henney</a>, <a href="/search/physics?searchtype=author&query=Jones-Mecholsky%2C+S+I">S. I. Jones-Mecholsky</a>, <a href="/search/physics?searchtype=author&query=Smith%2C+W+P">W. P. Smith</a>, <a href="/search/physics?searchtype=author&query=Bale%2C+S+D">S. D. Bale</a>, <a href="/search/physics?searchtype=author&query=Bonnell%2C+J+W">J. W. Bonnell</a>, <a href="/search/physics?searchtype=author&query=de+Wit%2C+T+D">T. Dudok de Wit</a>, <a href="/search/physics?searchtype=author&query=Goetz%2C+K">K. Goetz</a>, <a href="/search/physics?searchtype=author&query=Harvey%2C+P+R">P. R. Harvey</a>, <a href="/search/physics?searchtype=author&query=MacDowall%2C+R+J">R. J. MacDowall</a>, <a href="/search/physics?searchtype=author&query=Malaspina%2C+D+M">D. M. Malaspina</a>, <a href="/search/physics?searchtype=author&query=Pulupa%2C+M">M. Pulupa</a>, <a href="/search/physics?searchtype=author&query=Kasper%2C+J+C">J. C. Kasper</a>, <a href="/search/physics?searchtype=author&query=Korreck%2C+K+E">K. E. Korreck</a>, <a href="/search/physics?searchtype=author&query=Stevens%2C+M">M. Stevens</a>, <a href="/search/physics?searchtype=author&query=Case%2C+A+W">A. W. Case</a>, <a href="/search/physics?searchtype=author&query=Whittlesey%2C+P">P. Whittlesey</a>, <a href="/search/physics?searchtype=author&query=Livi%2C+R">R. Livi</a>, <a href="/search/physics?searchtype=author&query=Larson%2C+D+E">D. E. Larson</a>, <a href="/search/physics?searchtype=author&query=Klein%2C+K+G">K. G. Klein</a>, <a href="/search/physics?searchtype=author&query=Zank%2C+G+P">G. P. Zank</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1912.02397v1-abstract-short" style="display: inline;"> Since the launch on 2018/08/12, Parker Solar Probe (PSP) has completed its first and second orbits around the Sun, having reached down to 35.7 solar radii at each perihelion. In anticipation of the exciting new data at such unprecedented distances, we have simulated the global 3D heliosphere using an MHD model coupled with a semi-empirical coronal model using the best available photospheric magnet… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1912.02397v1-abstract-full').style.display = 'inline'; document.getElementById('1912.02397v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1912.02397v1-abstract-full" style="display: none;"> Since the launch on 2018/08/12, Parker Solar Probe (PSP) has completed its first and second orbits around the Sun, having reached down to 35.7 solar radii at each perihelion. In anticipation of the exciting new data at such unprecedented distances, we have simulated the global 3D heliosphere using an MHD model coupled with a semi-empirical coronal model using the best available photospheric magnetograms as input. We compare our heliospheric MHD simulation results with in situ measurements along the PSP trajectory from its launch to the completion of the second orbit, with particular emphasis on the solar wind structure around the first two solar encounters. Furthermore, we show our model prediction for the third perihelion, which occurred on 2019/09/01. Comparison of the MHD results with PSP observations provides a new insight on the solar wind acceleration. Moreover, PSP observations reveal how accurately the ADAPT-WSA predictions work throughout the inner heliosphere. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1912.02397v1-abstract-full').style.display = 'none'; document.getElementById('1912.02397v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 5 December, 2019; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> December 2019. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1912.02372">arXiv:1912.02372</a> <span> [<a href="https://arxiv.org/pdf/1912.02372">pdf</a>, <a href="https://arxiv.org/format/1912.02372">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Space Physics">physics.space-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.3847/1538-4365/ab5852">10.3847/1538-4365/ab5852 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Turbulence Transport Modeling and First Orbit Parker Solar Probe (PSP) Observations </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Adhikari%2C+L">Laxman Adhikari</a>, <a href="/search/physics?searchtype=author&query=Zank%2C+G+P">Gary P. Zank</a>, <a href="/search/physics?searchtype=author&query=Zhao%2C+L">Lingling Zhao</a>, <a href="/search/physics?searchtype=author&query=Kasper%2C+J+C">Justin C. Kasper</a>, <a href="/search/physics?searchtype=author&query=Korreck%2C+K+E">Kelly E. Korreck</a>, <a href="/search/physics?searchtype=author&query=Stevens%2C+M">Michael Stevens</a>, <a href="/search/physics?searchtype=author&query=Case%2C+A+W">Anthony W Case</a>, <a href="/search/physics?searchtype=author&query=Whittlesey%2C+P">Phyllis Whittlesey</a>, <a href="/search/physics?searchtype=author&query=Larson%2C+D">Davin Larson</a>, <a href="/search/physics?searchtype=author&query=Livi%2C+R">Roberto Livi</a>, <a href="/search/physics?searchtype=author&query=Klein%2C+K+G">Kristopher G. Klein</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1912.02372v1-abstract-short" style="display: inline;"> Parker Solar Probe (PSP) achieved its first orbit perihelion on November 6, 2018, reaching a heliocentric distance of about 0.165 au (35.55 R$_\odot$). Here, we study the evolution of fully developed turbulence associated with the slow solar wind along the PSP trajectory between 35.55 R$_\odot$ and 131.64 R$_\odot$ in the outbound direction, comparing observations to a theoretical turbulence trans… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1912.02372v1-abstract-full').style.display = 'inline'; document.getElementById('1912.02372v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1912.02372v1-abstract-full" style="display: none;"> Parker Solar Probe (PSP) achieved its first orbit perihelion on November 6, 2018, reaching a heliocentric distance of about 0.165 au (35.55 R$_\odot$). Here, we study the evolution of fully developed turbulence associated with the slow solar wind along the PSP trajectory between 35.55 R$_\odot$ and 131.64 R$_\odot$ in the outbound direction, comparing observations to a theoretical turbulence transport model. Several turbulent quantities, such as the fluctuating kinetic energy and the corresponding correlation length, the variance of density fluctuations, and the solar wind proton temperature are determined from the PSP SWEAP plasma data along its trajectory between 35.55 R$_\odot$ and 131.64 R$_\odot$. The evolution of the PSP derived turbulent quantities are compared to the numerical solutions of the nearly incompressible magnetohydrodynamic (NI MHD) turbulence transport model recently developed by Zank et al. (2017). We find reasonable agreement between the theoretical and observed results. On the basis of these comparisons, we derive other theoretical turbulent quantities, such as the energy in forward and backward propagating modes, the total turbulent energy, the normalized residual energy and cross-helicity, the fluctuating magnetic energy, and the correlation lengths corresponding to forward and backward propagating modes, the residual energy, and the fluctuating magnetic energy. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1912.02372v1-abstract-full').style.display = 'none'; document.getElementById('1912.02372v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 4 December, 2019; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> December 2019. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1912.02361">arXiv:1912.02361</a> <span> [<a href="https://arxiv.org/pdf/1912.02361">pdf</a>, <a href="https://arxiv.org/format/1912.02361">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Solar and Stellar Astrophysics">astro-ph.SR</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Space Physics">physics.space-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.3847/1538-4365/ab6c65">10.3847/1538-4365/ab6c65 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Ion Scale Electromagnetic Waves in the Inner Heliosphere </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Bowen%2C+T">Trevor Bowen</a>, <a href="/search/physics?searchtype=author&query=Mallet%2C+A">Alfred Mallet</a>, <a href="/search/physics?searchtype=author&query=Huang%2C+J">Jia Huang</a>, <a href="/search/physics?searchtype=author&query=Klein%2C+K+G">Kristopher G. Klein</a>, <a href="/search/physics?searchtype=author&query=Malaspina%2C+D+M">David M. Malaspina</a>, <a href="/search/physics?searchtype=author&query=Stevens%2C+M+L">Michael L. Stevens</a>, <a href="/search/physics?searchtype=author&query=Bale%2C+S+D">Stuart D. Bale</a>, <a href="/search/physics?searchtype=author&query=Bonnell%2C+J+W">John W. Bonnell</a>, <a href="/search/physics?searchtype=author&query=Case%2C+A+W">Anthony W. Case</a>, <a href="/search/physics?searchtype=author&query=Chandran%2C+B+D">Benjamin D. Chandran</a>, <a href="/search/physics?searchtype=author&query=Chaston%2C+C">Christopher Chaston</a>, <a href="/search/physics?searchtype=author&query=Chen%2C+C+H">Christopher H. Chen</a>, <a href="/search/physics?searchtype=author&query=de+Wit%2C+T+D">Thierry Dudok de Wit</a>, <a href="/search/physics?searchtype=author&query=Goetz%2C+K">Keith Goetz</a>, <a href="/search/physics?searchtype=author&query=Harvey%2C+P+R">Peter R. Harvey</a>, <a href="/search/physics?searchtype=author&query=Howes%2C+G+G">Gregory G. Howes</a>, <a href="/search/physics?searchtype=author&query=Kasper%2C+J+C">Justin C. Kasper</a>, <a href="/search/physics?searchtype=author&query=Korreck%2C+K">Kelly Korreck</a>, <a href="/search/physics?searchtype=author&query=Larson%2C+D+E">Davin E. Larson</a>, <a href="/search/physics?searchtype=author&query=Livi%2C+R">Roberto Livi</a>, <a href="/search/physics?searchtype=author&query=MacDowall%2C+R+J">Robert J. MacDowall</a>, <a href="/search/physics?searchtype=author&query=McManus%2C+M">Michael McManus</a>, <a href="/search/physics?searchtype=author&query=Pulupa%2C+M">Marc Pulupa</a>, <a href="/search/physics?searchtype=author&query=Verniero%2C+J">J Verniero</a>, <a href="/search/physics?searchtype=author&query=Whittlesey%2C+P">Phyllis Whittlesey</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1912.02361v1-abstract-short" style="display: inline;"> Understanding the physical processes in the solar wind and corona which actively contribute to heating, acceleration, and dissipation is a primary objective of NASA's Parker Solar Probe (PSP) mission. Observations of coherent electromagnetic waves at ion scales suggests that linear cyclotron resonance and non-linear processes are dynamically relevant in the inner heliosphere. A wavelet-based stati… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1912.02361v1-abstract-full').style.display = 'inline'; document.getElementById('1912.02361v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1912.02361v1-abstract-full" style="display: none;"> Understanding the physical processes in the solar wind and corona which actively contribute to heating, acceleration, and dissipation is a primary objective of NASA's Parker Solar Probe (PSP) mission. Observations of coherent electromagnetic waves at ion scales suggests that linear cyclotron resonance and non-linear processes are dynamically relevant in the inner heliosphere. A wavelet-based statistical study of coherent waves in the first perihelion encounter of PSP demonstrates the presence of transverse electromagnetic waves at ion resonant scales which are observed in 30-50\% of radial field intervals. Average wave amplitudes of approximately 4 nT are measured, while the mean duration of wave events is of order 20 seconds; however long duration wave events can exist without interruption on hour-long timescales. Though ion scale waves are preferentially observed during intervals with a radial mean magnetic field, we show that measurement constraints, associated with single spacecraft sampling of quasi-parallel waves superposed with anisotropic turbulence, render the measured quasi-parallel ion-wave spectrum unobservable when the mean magnetic field is oblique to the solar wind flow; these results imply that the occurrence of coherent ion-scale waves is not limited to a radial field configuration. The lack of strong radial scaling of characteristic wave amplitudes and duration suggests that the waves are generated {\em{in-situ}} through plasma instabilities. Additionally, observations of proton distribution functions indicate that temperature anisotropy may drive the observed ion-scale waves. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1912.02361v1-abstract-full').style.display = 'none'; document.getElementById('1912.02361v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 4 December, 2019; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> December 2019. </p> </li> </ol> <nav class="pagination is-small is-centered breathe-horizontal" role="navigation" aria-label="pagination"> <a href="" class="pagination-previous is-invisible">Previous </a> <a href="/search/?searchtype=author&query=Case%2C+A+W&start=50" class="pagination-next" >Next </a> <ul class="pagination-list"> <li> <a href="/search/?searchtype=author&query=Case%2C+A+W&start=0" 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