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</div> <div class="control"> <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=Kochukhov%2C+O&start=50" class="pagination-next" >Next </a> <ul class="pagination-list"> <li> <a href="/search/?searchtype=author&query=Kochukhov%2C+O&start=0" class="pagination-link is-current" aria-label="Goto page 1">1 </a> </li> <li> <a href="/search/?searchtype=author&query=Kochukhov%2C+O&start=50" class="pagination-link " aria-label="Page 2" aria-current="page">2 </a> </li> <li> <a href="/search/?searchtype=author&query=Kochukhov%2C+O&start=100" class="pagination-link " aria-label="Page 3" aria-current="page">3 </a> </li> <li> <a href="/search/?searchtype=author&query=Kochukhov%2C+O&start=150" class="pagination-link " aria-label="Page 4" 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is-tooltip-top" data-tooltip="Instrumentation and Methods for Astrophysics">astro-ph.IM</span> </div> </div> <p class="title is-5 mathjax"> Performance of the Stellar Abundances and atmospheric Parameters Pipeline adapted for M dwarfs I. Atmospheric parameters from the spectroscopic module </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Olander%2C+T">Terese Olander</a>, <a href="/search/astro-ph?searchtype=author&query=Gent%2C+M+R">Matthew R. Gent</a>, <a href="/search/astro-ph?searchtype=author&query=Heiter%2C+U">Ulrike Heiter</a>, <a href="/search/astro-ph?searchtype=author&query=Kochukhov%2C+O">Oleg Kochukhov</a>, <a href="/search/astro-ph?searchtype=author&query=Bergemann%2C+M">Maria Bergemann</a>, <a href="/search/astro-ph?searchtype=author&query=Magg%2C+E">Ekaterina Magg</a>, <a href="/search/astro-ph?searchtype=author&query=Cassisi%2C+S">Santi Cassisi</a>, <a href="/search/astro-ph?searchtype=author&query=Kovalev%2C+M">Mikhail Kovalev</a>, <a href="/search/astro-ph?searchtype=author&query=Morel%2C+T">Thierry Morel</a>, <a href="/search/astro-ph?searchtype=author&query=Miller%2C+N+J">Nicola J. Miller</a>, <a href="/search/astro-ph?searchtype=author&query=Souto%2C+D">Diogo Souto</a>, <a href="/search/astro-ph?searchtype=author&query=Shan%2C+Y">Yutong Shan</a>, <a href="/search/astro-ph?searchtype=author&query=Rojas-Ayala%2C+B">B谩rbara Rojas-Ayala</a>, <a href="/search/astro-ph?searchtype=author&query=Delgado-Mena%2C+E">Elisa Delgado-Mena</a>, <a href="/search/astro-ph?searchtype=author&query=Wang%2C+H+S">Haiyang S. Wang</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="2502.09388v1-abstract-short" style="display: inline;"> M dwarfs are important targets in the search for Earth-like exoplanets due to their small masses and low luminosities. Several ongoing and upcoming space missions are targeting M dwarfs for this reason, and the ESA PLATO mission is one of these. In order to fully characterise a planetary system the properties of the host star must be known. For M dwarfs we can derive effective temperature, surface… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2502.09388v1-abstract-full').style.display = 'inline'; document.getElementById('2502.09388v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2502.09388v1-abstract-full" style="display: none;"> M dwarfs are important targets in the search for Earth-like exoplanets due to their small masses and low luminosities. Several ongoing and upcoming space missions are targeting M dwarfs for this reason, and the ESA PLATO mission is one of these. In order to fully characterise a planetary system the properties of the host star must be known. For M dwarfs we can derive effective temperature, surface gravity, metallicity, and abundances of various elements from spectroscopic observations in combination with photometric data. The Stellar Abundances and atmospheric Parameters Pipeline (SAPP) has been developed as a prototype for one of the stellar science softwares within the PLATO consortium, it is aimed at FGK stars. We have modified it to be able to analyse the M dwarf among the PLATO targets. The current version of the pipeline for M dwarfs mostly relies on spectroscopic observations. The data processing is based on the machine learning algorithm The Payne and fits a grid of model spectra to an observed spectrum to derive effective temperature and metallicity. We use spectra in the H-band, as the near-infrared region is beneficial for M dwarfs. A method based on synthetic spectra was developed for the continuum normalisation of the spectra, taking into account the pseudo-continuum formed by numerous lines of the water molecule. Photometry is used to constrain the surface gravity. We tested the modified SAPP on spectra of M dwarfs from the APOGEE survey. Our validation sample of 26 stars includes stars with interferometric observations and binaries. We found a good agreement between our values and reference values from a range of studies. The overall uncertainties in the derived effective temperature, surface gravity, and metallicity is 100 K, 0.1 dex, and 0.15 dex, respectively. We find that the modified SAPP performs well on M dwarfs and identify possible areas of future development. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2502.09388v1-abstract-full').style.display = 'none'; document.getElementById('2502.09388v1-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 February, 2025; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> February 2025. </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 A&A</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2501.19169">arXiv:2501.19169</a> <span> [<a href="https://arxiv.org/pdf/2501.19169">pdf</a>, <a href="https://arxiv.org/format/2501.19169">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> </div> </div> <p class="title is-5 mathjax"> Testing the Rossby Paradigm: Weakened Magnetic Braking in early K-type Stars </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Metcalfe%2C+T+S">Travis S. Metcalfe</a>, <a href="/search/astro-ph?searchtype=author&query=Petit%2C+P">Pascal Petit</a>, <a href="/search/astro-ph?searchtype=author&query=van+Saders%2C+J+L">Jennifer L. van Saders</a>, <a href="/search/astro-ph?searchtype=author&query=Ayres%2C+T+R">Thomas R. Ayres</a>, <a href="/search/astro-ph?searchtype=author&query=Buzasi%2C+D">Derek Buzasi</a>, <a href="/search/astro-ph?searchtype=author&query=Kochukhov%2C+O">Oleg Kochukhov</a>, <a href="/search/astro-ph?searchtype=author&query=Stassun%2C+K+G">Keivan G. Stassun</a>, <a href="/search/astro-ph?searchtype=author&query=Pinsonneault%2C+M+H">Marc H. Pinsonneault</a>, <a href="/search/astro-ph?searchtype=author&query=Ilyin%2C+I+V">Ilya V. Ilyin</a>, <a href="/search/astro-ph?searchtype=author&query=Strassmeier%2C+K+G">Klaus G. Strassmeier</a>, <a href="/search/astro-ph?searchtype=author&query=Finley%2C+A+J">Adam J. Finley</a>, <a href="/search/astro-ph?searchtype=author&query=Garcia%2C+R+A">Rafael A. Garcia</a>, <a href="/search/astro-ph?searchtype=author&query=Yuxi"> Yuxi</a>, <a href="/search/astro-ph?searchtype=author&query=Lu"> Lu</a>, <a href="/search/astro-ph?searchtype=author&query=See%2C+V">Victor See</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="2501.19169v1-abstract-short" style="display: inline;"> There is an intricate relationship between the organization of large-scale magnetic fields by a stellar dynamo and the rate of angular momentum loss due to magnetized stellar winds. An essential ingredient for the operation of a large-scale dynamo is the Coriolis force, which imprints organizing flows on the global convective patterns and inhibits the complete cancellation of bipolar magnetic regi… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2501.19169v1-abstract-full').style.display = 'inline'; document.getElementById('2501.19169v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2501.19169v1-abstract-full" style="display: none;"> There is an intricate relationship between the organization of large-scale magnetic fields by a stellar dynamo and the rate of angular momentum loss due to magnetized stellar winds. An essential ingredient for the operation of a large-scale dynamo is the Coriolis force, which imprints organizing flows on the global convective patterns and inhibits the complete cancellation of bipolar magnetic regions. Consequently, it is natural to expect a rotational threshold for large-scale dynamo action and for the efficient angular momentum loss that it mediates through magnetic braking. Here we present new observational constraints on magnetic braking for an evolutionary sequence of six early K-type stars. To determine the wind braking torque for each of our targets, we combine spectropolarimetric constraints on the large-scale magnetic field, Ly-alpha or X-ray constraints on the mass-loss rate, as well as uniform estimates of the stellar rotation period, mass, and radius. As identified previously from similar observations of hotter stars, we find that the wind braking torque decreases abruptly by more than an order of magnitude at a critical value of the stellar Rossby number. Given that all of the stars in our sample exhibit clear activity cycles, we suggest that weakened magnetic braking may coincide with the operation of a subcritical stellar dynamo. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2501.19169v1-abstract-full').style.display = 'none'; document.getElementById('2501.19169v1-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, 2025; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> January 2025. </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">14 pages including 5 figures and 1 table. Under second review at AAS Journals</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2501.01321">arXiv:2501.01321</a> <span> [<a href="https://arxiv.org/pdf/2501.01321">pdf</a>, <a href="https://arxiv.org/format/2501.01321">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="High Energy Astrophysical Phenomena">astro-ph.HE</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="High Energy Physics - Phenomenology">hep-ph</span> </div> </div> <p class="title is-5 mathjax"> Multi-Observatory Study of Young Stellar Energetic Flares (MORYSEF): No Evidence For Abnormally Strong Stellar Magnetic Fields After Powerful X-ray Flares </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Getman%2C+K+V">Konstantin V. Getman</a>, <a href="/search/astro-ph?searchtype=author&query=Kochukhov%2C+O">Oleg Kochukhov</a>, <a href="/search/astro-ph?searchtype=author&query=Ninan%2C+J+P">Joe P. Ninan</a>, <a href="/search/astro-ph?searchtype=author&query=Feigelson%2C+E+D">Eric D. Feigelson</a>, <a href="/search/astro-ph?searchtype=author&query=Airapetian%2C+V+S">Vladimir S. Airapetian</a>, <a href="/search/astro-ph?searchtype=author&query=Waggoner%2C+A+R">Abygail R. Waggoner</a>, <a href="/search/astro-ph?searchtype=author&query=Cleeves%2C+L+I">L. Ilsedore Cleeves</a>, <a href="/search/astro-ph?searchtype=author&query=Forbrich%2C+J">Jan Forbrich</a>, <a href="/search/astro-ph?searchtype=author&query=Dzib%2C+S+A">Sergio A. Dzib</a>, <a href="/search/astro-ph?searchtype=author&query=Law%2C+C+J">Charles J. Law</a>, <a href="/search/astro-ph?searchtype=author&query=Rab%2C+C">Christian Rab</a>, <a href="/search/astro-ph?searchtype=author&query=Krolikowski%2C+D+M">Daniel M. Krolikowski</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="2501.01321v1-abstract-short" style="display: inline;"> We explore the empirical power-law relationship between X-ray luminosity (Lx) and total surface magnetic flux (Phi), established across solar magnetic elements, time- and disk-averaged emission from the Sun, older active stars, and pre-main-sequence (PMS) stars. Previous models of large PMS X-ray flares, lacking direct magnetic field measurements, showed discrepancies from this baseline law, which… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2501.01321v1-abstract-full').style.display = 'inline'; document.getElementById('2501.01321v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2501.01321v1-abstract-full" style="display: none;"> We explore the empirical power-law relationship between X-ray luminosity (Lx) and total surface magnetic flux (Phi), established across solar magnetic elements, time- and disk-averaged emission from the Sun, older active stars, and pre-main-sequence (PMS) stars. Previous models of large PMS X-ray flares, lacking direct magnetic field measurements, showed discrepancies from this baseline law, which MHD simulations attribute to unusually strong magnetic fields during flares. To test this, we used nearly simultaneous Chandra X-ray and HET-HPF near-infrared observations of four young Orion stars, measuring surface magnetic fields during or just after powerful PMS X-ray flares. We also modeled these PMS X-ray flares, incorporating their measured magnetic field strengths. Our findings reveal magnetic field strengths at the stellar surface typical of non-flaring PMS stars, ruling out the need for abnormally strong fields during flares. Both PMS and solar flares deviate from the Lx-Phi law, with PMS flares exhibiting a more pronounced deviation, primarily due to their much larger active regions on the surface and larger flaring loop volumes above the surface compared to their solar counterparts. These deviations likely stem from the fact that powerful flares are driven by magnetic reconnection, while baseline X-ray emission may involve less efficient mechanisms like Alfven wave heating. Our results also indicate a preference for dipolar magnetic loops in PMS flares, consistent with Zeeman-Doppler imaging of fully convective stars. This requirement for giant dipolar loops aligns with MHD predictions of strong dipoles supported by polar magnetic surface active regions in fast-rotating, fully convective stars. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2501.01321v1-abstract-full').style.display = 'none'; document.getElementById('2501.01321v1-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> 2 January, 2025; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> January 2025. </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">25 pages, 9 figures, 3 tables. Accepted for publication in The Astrophysical Journal, January 1, 2025</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2411.05376">arXiv:2411.05376</a> <span> [<a href="https://arxiv.org/pdf/2411.05376">pdf</a>, <a href="https://arxiv.org/format/2411.05376">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> </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/stae2503">10.1093/mnras/stae2503 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> HD 34736: An intensely magnetised double-lined spectroscopic binary with rapidly-rotating chemically peculiar B-type components </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Semenko%2C+E">E. Semenko</a>, <a href="/search/astro-ph?searchtype=author&query=Kochukhov%2C+O">O. Kochukhov</a>, <a href="/search/astro-ph?searchtype=author&query=Mikul%C3%A1%C5%A1ek%2C+Z">Z. Mikul谩拧ek</a>, <a href="/search/astro-ph?searchtype=author&query=Wade%2C+G+A">G. A. Wade</a>, <a href="/search/astro-ph?searchtype=author&query=Alecian%2C+E">E. Alecian</a>, <a href="/search/astro-ph?searchtype=author&query=Bohlender%2C+D">D. Bohlender</a>, <a href="/search/astro-ph?searchtype=author&query=Das%2C+B">B. Das</a>, <a href="/search/astro-ph?searchtype=author&query=Feliz%2C+D+L">D. L. Feliz</a>, <a href="/search/astro-ph?searchtype=author&query=Jan%C3%ADk%2C+J">J. Jan铆k</a>, <a href="/search/astro-ph?searchtype=author&query=Kola%C5%99%2C+J">J. Kola艡</a>, <a href="/search/astro-ph?searchtype=author&query=Krti%C4%8Dka%2C+J">J. Krti膷ka</a>, <a href="/search/astro-ph?searchtype=author&query=Kudryavtsev%2C+D+O">D. O. Kudryavtsev</a>, <a href="/search/astro-ph?searchtype=author&query=Labadie-Bartz%2C+J+M">J. M. Labadie-Bartz</a>, <a href="/search/astro-ph?searchtype=author&query=Mkrtichian%2C+D">D. Mkrtichian</a>, <a href="/search/astro-ph?searchtype=author&query=Monin%2C+D">D. Monin</a>, <a href="/search/astro-ph?searchtype=author&query=Petit%2C+V">V. Petit</a>, <a href="/search/astro-ph?searchtype=author&query=Romanyuk%2C+I+I">I. I. Romanyuk</a>, <a href="/search/astro-ph?searchtype=author&query=Shultz%2C+M+E">M. E. Shultz</a>, <a href="/search/astro-ph?searchtype=author&query=Shulyak%2C+D">D. Shulyak</a>, <a href="/search/astro-ph?searchtype=author&query=Siverd%2C+R+J">R. J. Siverd</a>, <a href="/search/astro-ph?searchtype=author&query=Tkachenko%2C+A">A. Tkachenko</a>, <a href="/search/astro-ph?searchtype=author&query=Yakunin%2C+I+A">I. A. Yakunin</a>, <a href="/search/astro-ph?searchtype=author&query=Zejda%2C+M">M. Zejda</a>, <a href="/search/astro-ph?searchtype=author&query=collaboration%2C+t+B">the BinaMIcS collaboration</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="2411.05376v1-abstract-short" style="display: inline;"> We report the results of a comprehensive study of the spectroscopic binary (SB2) system HD 34736 hosting two chemically peculiar (CP) late B-type stars. Using new and archival observational data, we characterise the system and its components, including their rotation and magnetic fields. Fitting of the radial velocities yields $P_\mathrm{orb}=83.\!^\mathrm{d}219(3)$ and $e=0.8103(3)$. The primary… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2411.05376v1-abstract-full').style.display = 'inline'; document.getElementById('2411.05376v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2411.05376v1-abstract-full" style="display: none;"> We report the results of a comprehensive study of the spectroscopic binary (SB2) system HD 34736 hosting two chemically peculiar (CP) late B-type stars. Using new and archival observational data, we characterise the system and its components, including their rotation and magnetic fields. Fitting of the radial velocities yields $P_\mathrm{orb}=83.\!^\mathrm{d}219(3)$ and $e=0.8103(3)$. The primary component is a CP He-wk star with $T_{\mathrm{eff}A}=13000\pm500$ K and $\upsilon_\mathrm{e}\sin i\;=75\pm3$ km/s, while the secondary exhibits variability of Mg and Si lines, and has $T_{\mathrm{eff}B}=11500\pm1000$ K and $\upsilon_\mathrm{e}\sin i=110$-180 km/s. TESS and KELT photometry reveal clear variability of the primary component with a rotational period $P_{\mathrm{rot}A}=1.\!^\mathrm{d}279\,988\,5(11)$, which is lengthening at a rate of $1.26(6)$ s/yr. For the secondary, $P_{\mathrm{rot}B}=0.\!^\mathrm{d}522\,693\,8(5)$, reducing at a rate of $-0.14(3)$ s/yr. The longitudinal component $\langle B_\mathrm{z}\rangle$ of the primary's strongly asymmetric global magnetic field varies from $-6$ to +5 kG. Weak spectropolarimetric evidence of a magnetic field is found for the secondary star. The observed X-ray and radio emission of HD 34736 may equally be linked to a suspected T Tau-like companion or magnetospheric emission from the principal components. Given the presence of a possible third magnetically active body, one can propose that the magnetic characteristics of the protostellar environment may be connected to the formation of such systems. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2411.05376v1-abstract-full').style.display = 'none'; document.getElementById('2411.05376v1-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 November, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> November 2024. </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 preprint has 28 pages, 23 figures, and includes the complete version of Table 1. Published in MNRAS</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2410.05126">arXiv:2410.05126</a> <span> [<a href="https://arxiv.org/pdf/2410.05126">pdf</a>, <a href="https://arxiv.org/format/2410.05126">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="High Energy Astrophysical Phenomena">astro-ph.HE</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="High Energy Physics - Phenomenology">hep-ph</span> </div> </div> <p class="title is-5 mathjax"> Multi-Observatory Research of Young Stellar Energetic Flares (MORYSEF): X-ray Flare Related Phenomena and Multi-epoch Behavior </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Getman%2C+K+V">Konstantin V. Getman</a>, <a href="/search/astro-ph?searchtype=author&query=Feigelson%2C+E+D">Eric D. Feigelson</a>, <a href="/search/astro-ph?searchtype=author&query=Waggoner%2C+A+R">Abygail R. Waggoner</a>, <a href="/search/astro-ph?searchtype=author&query=Cleeves%2C+L+I">L. Ilsedore Cleeves</a>, <a href="/search/astro-ph?searchtype=author&query=Forbrich%2C+J">Jan Forbrich</a>, <a href="/search/astro-ph?searchtype=author&query=Ninan%2C+J+P">Joe P. Ninan</a>, <a href="/search/astro-ph?searchtype=author&query=Kochukhov%2C+O">Oleg Kochukhov</a>, <a href="/search/astro-ph?searchtype=author&query=Airapetian%2C+V+S">Vladimir S. Airapetian</a>, <a href="/search/astro-ph?searchtype=author&query=Dzib%2C+S+A">Sergio A. Dzib</a>, <a href="/search/astro-ph?searchtype=author&query=Law%2C+C+J">Charles J. Law</a>, <a href="/search/astro-ph?searchtype=author&query=Rab%2C+C">Christian Rab</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="2410.05126v1-abstract-short" style="display: inline;"> The most powerful stellar flares driven by magnetic energy occur during the early pre-main sequence (PMS) phase. The Orion Nebula represents the nearest region populated by young stars, showing the greatest number of flares accessible to a single pointing of Chandra. This study is part of a multi-observatory project to explore stellar surface magnetic fields (with HET-HPF), particle ejections (VLB… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2410.05126v1-abstract-full').style.display = 'inline'; document.getElementById('2410.05126v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2410.05126v1-abstract-full" style="display: none;"> The most powerful stellar flares driven by magnetic energy occur during the early pre-main sequence (PMS) phase. The Orion Nebula represents the nearest region populated by young stars, showing the greatest number of flares accessible to a single pointing of Chandra. This study is part of a multi-observatory project to explore stellar surface magnetic fields (with HET-HPF), particle ejections (VLBA), and disk ionization (ALMA) immediately following the detection of PMS super-flares with Chandra. In December 2023, we successfully conducted such a multi-telescope campaign. Additionally, by analyzing Chandra data from 2003, 2012, and 2016, we examine the multi-epoch behavior of PMS X-ray emission related to PMS magnetic cyclic activity and ubiquitous versus sample-confined mega-flaring. Our findings follow. 1) We report detailed stellar quiescent and flare X-ray properties for numerous HET/ALMA/VLBA targets, facilitating ongoing multi-wavelength analyses. 2) For numerous moderately energetic flares, we report correlations (or lack thereof) between flare energies and stellar mass/size (presence/absence of disks) for the first time. The former is attributed to the correlation between convection-driven dynamo and stellar volume, while the latter suggests the operation of solar-type flare mechanisms in PMS stars. 3) We find that most PMS stars exhibit minor long-term baseline variations, indicating the absence of intrinsic magnetic dynamo cycles or observational mitigation of cycles by saturated PMS X-rays. 4) We conclude that X-ray mega-flares are ubiquitous phenomena in PMS stars, which suggests that all protoplanetary disks and nascent planets are subject to violent high-energy emission and particle irradiation events. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2410.05126v1-abstract-full').style.display = 'none'; document.getElementById('2410.05126v1-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> 7 October, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> October 2024. </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">32 pages, 9 figures, 8 tables. Accepted for publication in The Astrophysical Journal, October 7, 2024</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2409.06637">arXiv:2409.06637</a> <span> [<a href="https://arxiv.org/pdf/2409.06637">pdf</a>, <a href="https://arxiv.org/format/2409.06637">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> </div> </div> <p class="title is-5 mathjax"> Magnetic Fields in a sample of planet-hosting M dwarf stars from Kepler, K2, and TESS observed by APOGEE </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Wanderley%2C+F">F谩bio Wanderley</a>, <a href="/search/astro-ph?searchtype=author&query=Cunha%2C+K">Katia Cunha</a>, <a href="/search/astro-ph?searchtype=author&query=Smith%2C+V">Verne Smith</a>, <a href="/search/astro-ph?searchtype=author&query=Kochukhov%2C+O">Oleg Kochukhov</a>, <a href="/search/astro-ph?searchtype=author&query=Souto%2C+D">Diogo Souto</a>, <a href="/search/astro-ph?searchtype=author&query=Prieto%2C+C+A">Carlos Allende Prieto</a>, <a href="/search/astro-ph?searchtype=author&query=Mahadevan%2C+S">Suvrath Mahadevan</a>, <a href="/search/astro-ph?searchtype=author&query=Majewski%2C+S">Steven Majewski</a>, <a href="/search/astro-ph?searchtype=author&query=Muirhead%2C+P">Philip Muirhead</a>, <a href="/search/astro-ph?searchtype=author&query=Pinsonneault%2C+M">Marc Pinsonneault</a>, <a href="/search/astro-ph?searchtype=author&query=Terrien%2C+R">Ryan Terrien</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="2409.06637v1-abstract-short" style="display: inline;"> Stellar magnetic fields have a major impact on space weather around exoplanets orbiting low-mass stars. From an analysis of Zeeman-broadened Fe I lines measured in near-infrared SDSS/APOGEE spectra, mean magnetic fields are determined for a sample of 29 M dwarf stars that host closely orbiting small exoplanets. The calculations employed the radiative transfer code Synmast and MARCS stellar model a… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2409.06637v1-abstract-full').style.display = 'inline'; document.getElementById('2409.06637v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2409.06637v1-abstract-full" style="display: none;"> Stellar magnetic fields have a major impact on space weather around exoplanets orbiting low-mass stars. From an analysis of Zeeman-broadened Fe I lines measured in near-infrared SDSS/APOGEE spectra, mean magnetic fields are determined for a sample of 29 M dwarf stars that host closely orbiting small exoplanets. The calculations employed the radiative transfer code Synmast and MARCS stellar model atmospheres. The sample M dwarfs are found to have measurable mean magnetic fields ranging between $\sim$0.2 to $\sim$1.5 kG, falling in the unsaturated regime on the $<$B$>$ vs P$_{\rm rot}$ plane. The sample systems contain 43 exoplanets, which include 23 from Kepler, nine from K2, and nine from TESS. We evaluated their equilibrium temperatures, insolation, and stellar habitable zones and found that only Kepler-186f and TOI-700d are inside the habitable zones of their stars. Using the derived values of $<$B$>$ for the stars Kepler-186 and TOI-700 we evaluated the minimum planetary magnetic field that would be necessary to shield the exoplanets Kepler-186f and TOI-700d from their host star's winds, considering reference magnetospheres with sizes equal to those of the present-day and young Earth, respectively. Assuming a ratio of 5$\%$ between large-to-small scale B-fields, and a young-Earth magnetosphere, Kepler-186f and TOI-700d would need minimum planetary magnetic fields of, respectively, 0.05 and 0.24 G. These values are considerably smaller than Earth's magnetic field of 0.25 G$\lesssim$B$\lesssim$0.65 G, which suggests that these two exoplanets might have magnetic fields sufficiently strong to protect their atmospheres and surfaces from stellar magnetic fields. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2409.06637v1-abstract-full').style.display = 'none'; document.getElementById('2409.06637v1-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 September, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> September 2024. </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 by The Astrophysical Journal (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/2407.15655">arXiv:2407.15655</a> <span> [<a href="https://arxiv.org/pdf/2407.15655">pdf</a>, <a href="https://arxiv.org/ps/2407.15655">ps</a>, <a href="https://arxiv.org/format/2407.15655">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> </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/10.1051/0004-6361/202451365">10.1051/0004-6361/202451365 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Imprint of the magnetic activity cycle on solar asteroseismic characterisation based on 26 years of GOLF and BiSON data </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=B%C3%A9trisey%2C+J">J茅r么me B茅trisey</a>, <a href="/search/astro-ph?searchtype=author&query=Farnir%2C+M">Martin Farnir</a>, <a href="/search/astro-ph?searchtype=author&query=Breton%2C+S+N">Sylvain N. Breton</a>, <a href="/search/astro-ph?searchtype=author&query=Garc%C3%ADa%2C+R+A">Rafael A. Garc铆a</a>, <a href="/search/astro-ph?searchtype=author&query=Broomhall%2C+A">Anne-Marie Broomhall</a>, <a href="/search/astro-ph?searchtype=author&query=Amarsi%2C+A+M">Anish M. Amarsi</a>, <a href="/search/astro-ph?searchtype=author&query=Kochukhov%2C+O">Oleg Kochukhov</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="2407.15655v1-abstract-short" style="display: inline;"> Building on the success of previous missions, asteroseismic modelling will play a key role in future space-based missions, such as PLATO, CubeSpec, and Roman. Despite remarkable achievements, asteroseismology has revealed significant discrepancies in the physics of theoretical stellar models, which have the potential to bias stellar characterisation at the precision level demanded by PLATO. The cu… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2407.15655v1-abstract-full').style.display = 'inline'; document.getElementById('2407.15655v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2407.15655v1-abstract-full" style="display: none;"> Building on the success of previous missions, asteroseismic modelling will play a key role in future space-based missions, such as PLATO, CubeSpec, and Roman. Despite remarkable achievements, asteroseismology has revealed significant discrepancies in the physics of theoretical stellar models, which have the potential to bias stellar characterisation at the precision level demanded by PLATO. The current modelling strategies largely overlook magnetic activity, assuming that its effects are masked by filtering the so-called surface effects. Given the presence of activity cycles in multiple solar-like oscillators, and activity variations in a significant fraction of Kepler observations of main-sequence stars (Santos et al. 2019b, 2021, 2023), we measured the impact of magnetic activity on the asteroseismic characterisation of the Sun based on 26.5 years of GOLF and BiSON observations. While magnetic activity is partially absorbed in the treatment of surface effects, we found a discernible imprint of the activity cycle in the determination of the solar age. Notably, this imprint persists across both BiSON and GOLF datasets, with significant variations of up to 6.5% observed between solar minima and maxima. Considering that the Sun exhibits low levels of activity, our study underscores the looming challenge posed by magnetic activity for future photometry missions, and prompts a potential reevaluation of the asteroseismic characterisation of Kepler's most active targets. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2407.15655v1-abstract-full').style.display = 'none'; document.getElementById('2407.15655v1-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 July, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> July 2024. </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 as a Letter in Astronomy and Astrophysics</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> A&A 688, L17 (2024) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2406.13757">arXiv:2406.13757</a> <span> [<a href="https://arxiv.org/pdf/2406.13757">pdf</a>, <a href="https://arxiv.org/format/2406.13757">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="Astrophysics of Galaxies">astro-ph.GA</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/ad571f">10.3847/1538-4357/ad571f <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Magnetic Fields of M Dwarfs from the Pleiades Open Cluster </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Wanderley%2C+F">Fabio Wanderley</a>, <a href="/search/astro-ph?searchtype=author&query=Cunha%2C+K">Katia Cunha</a>, <a href="/search/astro-ph?searchtype=author&query=Kochukhov%2C+O">Oleg Kochukhov</a>, <a href="/search/astro-ph?searchtype=author&query=Smith%2C+V+V">Verne V. Smith</a>, <a href="/search/astro-ph?searchtype=author&query=Souto%2C+D">Diogo Souto</a>, <a href="/search/astro-ph?searchtype=author&query=Cao%2C+L">Lyra Cao</a>, <a href="/search/astro-ph?searchtype=author&query=Covey%2C+K">Kevin Covey</a>, <a href="/search/astro-ph?searchtype=author&query=Majewski%2C+S+R">Steven R. Majewski</a>, <a href="/search/astro-ph?searchtype=author&query=Martinez%2C+C">Cintia Martinez</a>, <a href="/search/astro-ph?searchtype=author&query=Muirhead%2C+P+S">Philip S. Muirhead</a>, <a href="/search/astro-ph?searchtype=author&query=Pinsonneault%2C+M">Marc Pinsonneault</a>, <a href="/search/astro-ph?searchtype=author&query=Prieto%2C+C+A">C. Allende Prieto</a>, <a href="/search/astro-ph?searchtype=author&query=Stassun%2C+K+G">Keivan G. Stassun</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="2406.13757v1-abstract-short" style="display: inline;"> Average magnetic field measurements are presented for 62 M-dwarf members of the Pleiades open cluster, derived from Zeeman-enhanced Fe I lines in the H-band. An MCMC methodology was employed to model magnetic filling factors using SDSS-IV APOGEE high-resolution spectra, along with the radiative transfer code SYNMAST, MARCS stellar atmosphere models, and the APOGEE DR17 spectral line list. There is… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2406.13757v1-abstract-full').style.display = 'inline'; document.getElementById('2406.13757v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2406.13757v1-abstract-full" style="display: none;"> Average magnetic field measurements are presented for 62 M-dwarf members of the Pleiades open cluster, derived from Zeeman-enhanced Fe I lines in the H-band. An MCMC methodology was employed to model magnetic filling factors using SDSS-IV APOGEE high-resolution spectra, along with the radiative transfer code SYNMAST, MARCS stellar atmosphere models, and the APOGEE DR17 spectral line list. There is a positive correlation between mean magnetic fields and stellar rotation, with slow-rotator stars (Rossby number, Ro$>$0.13) exhibiting a steeper slope than rapid-rotators (Ro$<$0.13). However, the latter sample still shows a positive trend between Ro and magnetic fields, which is given by $<$B$>$ = 1604 $\times$ Ro$^{-0.20}$. The derived stellar radii, when compared with physical isochrones, show that on average, our sample shows radius inflation, with median enhanced radii ranging from +3.0$\%$ to +7.0$\%$, depending on the model. There is a positive correlation between magnetic field strength and radius inflation, as well as with stellar spot coverage, correlations that together indicate that stellar spot-filling factors generated by strong magnetic fields might be the mechanism that drives radius inflation in these stars. We also compare our derived magnetic fields with chromospheric emission lines (H$伪$, H$尾$ and Ca II K), as well as with X-ray and H$伪$ to bolometric luminosity ratios, and find that stars with higher chromospheric and coronal activity tend to be more magnetic. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2406.13757v1-abstract-full').style.display = 'none'; document.getElementById('2406.13757v1-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 June, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> June 2024. </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 by The Astrophysical Journal (ApJ); doi:10.3847/1538-4357/ad571f</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2406.08166">arXiv:2406.08166</a> <span> [<a href="https://arxiv.org/pdf/2406.08166">pdf</a>, <a href="https://arxiv.org/format/2406.08166">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Earth and Planetary Astrophysics">astro-ph.EP</span> </div> </div> <p class="title is-5 mathjax"> Exploring the ultra-hot Jupiter WASP-178b. Constraints on atmospheric chemistry and dynamics from a joint retrieval of VLT/CRIRES$^+$ and space photometric data </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Cont%2C+D">D. Cont</a>, <a href="/search/astro-ph?searchtype=author&query=Nortmann%2C+L">L. Nortmann</a>, <a href="/search/astro-ph?searchtype=author&query=Yan%2C+F">F. Yan</a>, <a href="/search/astro-ph?searchtype=author&query=Lesjak%2C+F">F. Lesjak</a>, <a href="/search/astro-ph?searchtype=author&query=Czesla%2C+S">S. Czesla</a>, <a href="/search/astro-ph?searchtype=author&query=Lavail%2C+A">A. Lavail</a>, <a href="/search/astro-ph?searchtype=author&query=Reiners%2C+A">A. Reiners</a>, <a href="/search/astro-ph?searchtype=author&query=Piskunov%2C+N">N. Piskunov</a>, <a href="/search/astro-ph?searchtype=author&query=Hatzes%2C+A">A. Hatzes</a>, <a href="/search/astro-ph?searchtype=author&query=Boldt-Christmas%2C+L">L. Boldt-Christmas</a>, <a href="/search/astro-ph?searchtype=author&query=Kochukhov%2C+O">O. Kochukhov</a>, <a href="/search/astro-ph?searchtype=author&query=Marquart%2C+T">T. Marquart</a>, <a href="/search/astro-ph?searchtype=author&query=Nagel%2C+E">E. Nagel</a>, <a href="/search/astro-ph?searchtype=author&query=Rains%2C+A+D">A. D. Rains</a>, <a href="/search/astro-ph?searchtype=author&query=Rengel%2C+M">M. Rengel</a>, <a href="/search/astro-ph?searchtype=author&query=Seemann%2C+U">U. Seemann</a>, <a href="/search/astro-ph?searchtype=author&query=Shulyak%2C+D">D. Shulyak</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="2406.08166v3-abstract-short" style="display: inline;"> Despite recent progress in the spectroscopic characterization of individual exoplanets, the atmospheres of key ultra-hot Jupiters (UHJs) still lack comprehensive investigations. These include WASP-178b, one of the most irradiated UHJs known to date. We observed the dayside emission signal of this planet with CRIRES$^+$ in the spectral K-band. By applying the cross-correlation technique and a Bayes… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2406.08166v3-abstract-full').style.display = 'inline'; document.getElementById('2406.08166v3-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2406.08166v3-abstract-full" style="display: none;"> Despite recent progress in the spectroscopic characterization of individual exoplanets, the atmospheres of key ultra-hot Jupiters (UHJs) still lack comprehensive investigations. These include WASP-178b, one of the most irradiated UHJs known to date. We observed the dayside emission signal of this planet with CRIRES$^+$ in the spectral K-band. By applying the cross-correlation technique and a Bayesian retrieval framework to the high-resolution spectra, we identified the emission signature of $^{12}$CO (S/N = 8.9) and H$_2$O (S/N = 4.9), and a strong atmospheric thermal inversion. A joint retrieval with space-based secondary eclipse measurements from TESS and CHEOPS allows us to refine our results on the thermal profile and thus to constrain the atmospheric chemistry, yielding a solar to super-solar metallicity (1.4$\pm$1.6 dex) and a solar C/O ratio (0.6$\pm$0.2). We infer a significant excess of spectral line broadening and identify a slight Doppler-shift between the $^{12}$CO and H$_2$O signals. These findings provide strong evidence for a super-rotating atmospheric flow pattern and suggest the possible existence of chemical inhomogeneities across the planetary dayside hemisphere. In addition, the inclusion of photometric data in our retrieval allows us to account for stellar light reflected by the planetary atmosphere, resulting in an upper limit on the geometric albedo (0.23). The successful characterization of WASP-178b's atmosphere through a joint analysis of CRIRES$^+$, TESS, and CHEOPS observations highlights the potential of combined studies with space- and ground-based instruments and represents a promising avenue for advancing our understanding of exoplanet atmospheres. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2406.08166v3-abstract-full').style.display = 'none'; document.getElementById('2406.08166v3-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 July, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 12 June, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> June 2024. </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 A&A</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2406.05447">arXiv:2406.05447</a> <span> [<a href="https://arxiv.org/pdf/2406.05447">pdf</a>, <a href="https://arxiv.org/format/2406.05447">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="Earth and Planetary Astrophysics">astro-ph.EP</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"> The PLATO Mission </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Rauer%2C+H">Heike Rauer</a>, <a href="/search/astro-ph?searchtype=author&query=Aerts%2C+C">Conny Aerts</a>, <a href="/search/astro-ph?searchtype=author&query=Cabrera%2C+J">Juan Cabrera</a>, <a href="/search/astro-ph?searchtype=author&query=Deleuil%2C+M">Magali Deleuil</a>, <a href="/search/astro-ph?searchtype=author&query=Erikson%2C+A">Anders Erikson</a>, <a href="/search/astro-ph?searchtype=author&query=Gizon%2C+L">Laurent Gizon</a>, <a href="/search/astro-ph?searchtype=author&query=Goupil%2C+M">Mariejo Goupil</a>, <a href="/search/astro-ph?searchtype=author&query=Heras%2C+A">Ana Heras</a>, <a href="/search/astro-ph?searchtype=author&query=Lorenzo-Alvarez%2C+J">Jose Lorenzo-Alvarez</a>, <a href="/search/astro-ph?searchtype=author&query=Marliani%2C+F">Filippo Marliani</a>, <a href="/search/astro-ph?searchtype=author&query=Martin-Garcia%2C+C">C茅sar Martin-Garcia</a>, <a href="/search/astro-ph?searchtype=author&query=Mas-Hesse%2C+J+M">J. Miguel Mas-Hesse</a>, <a href="/search/astro-ph?searchtype=author&query=O%27Rourke%2C+L">Laurence O'Rourke</a>, <a href="/search/astro-ph?searchtype=author&query=Osborn%2C+H">Hugh Osborn</a>, <a href="/search/astro-ph?searchtype=author&query=Pagano%2C+I">Isabella Pagano</a>, <a href="/search/astro-ph?searchtype=author&query=Piotto%2C+G">Giampaolo Piotto</a>, <a href="/search/astro-ph?searchtype=author&query=Pollacco%2C+D">Don Pollacco</a>, <a href="/search/astro-ph?searchtype=author&query=Ragazzoni%2C+R">Roberto Ragazzoni</a>, <a href="/search/astro-ph?searchtype=author&query=Ramsay%2C+G">Gavin Ramsay</a>, <a href="/search/astro-ph?searchtype=author&query=Udry%2C+S">St茅phane Udry</a>, <a href="/search/astro-ph?searchtype=author&query=Appourchaux%2C+T">Thierry Appourchaux</a>, <a href="/search/astro-ph?searchtype=author&query=Benz%2C+W">Willy Benz</a>, <a href="/search/astro-ph?searchtype=author&query=Brandeker%2C+A">Alexis Brandeker</a>, <a href="/search/astro-ph?searchtype=author&query=G%C3%BCdel%2C+M">Manuel G眉del</a>, <a href="/search/astro-ph?searchtype=author&query=Janot-Pacheco%2C+E">Eduardo Janot-Pacheco</a> , et al. (820 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="2406.05447v2-abstract-short" style="display: inline;"> PLATO (PLAnetary Transits and Oscillations of stars) is ESA's M3 mission designed to detect and characterise extrasolar planets and perform asteroseismic monitoring of a large number of stars. PLATO will detect small planets (down to <2 R_(Earth)) around bright stars (<11 mag), including terrestrial planets in the habitable zone of solar-like stars. With the complement of radial velocity observati… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2406.05447v2-abstract-full').style.display = 'inline'; document.getElementById('2406.05447v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2406.05447v2-abstract-full" style="display: none;"> PLATO (PLAnetary Transits and Oscillations of stars) is ESA's M3 mission designed to detect and characterise extrasolar planets and perform asteroseismic monitoring of a large number of stars. PLATO will detect small planets (down to <2 R_(Earth)) around bright stars (<11 mag), including terrestrial planets in the habitable zone of solar-like stars. With the complement of radial velocity observations from the ground, planets will be characterised for their radius, mass, and age with high accuracy (5 %, 10 %, 10 % for an Earth-Sun combination respectively). PLATO will provide us with a large-scale catalogue of well-characterised small planets up to intermediate orbital periods, relevant for a meaningful comparison to planet formation theories and to better understand planet evolution. It will make possible comparative exoplanetology to place our Solar System planets in a broader context. In parallel, PLATO will study (host) stars using asteroseismology, allowing us to determine the stellar properties with high accuracy, substantially enhancing our knowledge of stellar structure and evolution. The payload instrument consists of 26 cameras with 12cm aperture each. For at least four years, the mission will perform high-precision photometric measurements. Here we review the science objectives, present PLATO's target samples and fields, provide an overview of expected core science performance as well as a description of the instrument and the mission profile at the beginning of the serial production of the flight cameras. PLATO is scheduled for a launch date end 2026. This overview therefore provides a summary of the mission to the community in preparation of the upcoming operational phases. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2406.05447v2-abstract-full').style.display = 'none'; document.getElementById('2406.05447v2-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 November, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 8 June, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> June 2024. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2405.12778">arXiv:2405.12778</a> <span> [<a href="https://arxiv.org/pdf/2405.12778">pdf</a>, <a href="https://arxiv.org/format/2405.12778">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> </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/10.1051/0004-6361/202450543">10.1051/0004-6361/202450543 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> A conclusive non-detection of magnetic field in the Am star o Peg with high-precision near-infrared spectroscopy </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Kochukhov%2C+O">O. Kochukhov</a>, <a href="/search/astro-ph?searchtype=author&query=Amarsi%2C+A+M">A. M. Amarsi</a>, <a href="/search/astro-ph?searchtype=author&query=Lavail%2C+A">A. Lavail</a>, <a href="/search/astro-ph?searchtype=author&query=Ruh%2C+H+L">H. L. Ruh</a>, <a href="/search/astro-ph?searchtype=author&query=Hahlin%2C+A">A. Hahlin</a>, <a href="/search/astro-ph?searchtype=author&query=Hatzes%2C+A">A. Hatzes</a>, <a href="/search/astro-ph?searchtype=author&query=Nagel%2C+E">E. Nagel</a>, <a href="/search/astro-ph?searchtype=author&query=Piskunov%2C+N">N. Piskunov</a>, <a href="/search/astro-ph?searchtype=author&query=Pouilly%2C+K">K. Pouilly</a>, <a href="/search/astro-ph?searchtype=author&query=Reiners%2C+A">A. Reiners</a>, <a href="/search/astro-ph?searchtype=author&query=Rengel%2C+M">M. Rengel</a>, <a href="/search/astro-ph?searchtype=author&query=Seemann%2C+U">U. Seemann</a>, <a href="/search/astro-ph?searchtype=author&query=Shulyak%2C+D">D. Shulyak</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="2405.12778v1-abstract-short" style="display: inline;"> The A-type metallic-line (Am) stars are typically considered to be non-magnetic or possessing very weak sub-G magnetic fields. This view has been repeatedly challenged in the literature, most commonly for the bright hot Am star o Peg. Several studies claimed to detect 1-2 kG field of unknown topology in this object, possibly indicating a new process of magnetic field generation in intermediate-mas… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2405.12778v1-abstract-full').style.display = 'inline'; document.getElementById('2405.12778v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2405.12778v1-abstract-full" style="display: none;"> The A-type metallic-line (Am) stars are typically considered to be non-magnetic or possessing very weak sub-G magnetic fields. This view has been repeatedly challenged in the literature, most commonly for the bright hot Am star o Peg. Several studies claimed to detect 1-2 kG field of unknown topology in this object, possibly indicating a new process of magnetic field generation in intermediate-mass stars. In this study, we revisit the evidence of a strong magnetic field in o Peg using new high-resolution spectropolarimetric observations and advanced spectral fitting techniques. The mean magnetic field strength in o Peg is estimated from the high-precision CRIRES+ measurement of near-infrared sulphur lines. This observation is modelled with a polarised radiative transfer code, including treatment of the departures from local thermodynamic equilibrium. In addition, the least-squares deconvolution multi-line technique is employed to derive longitudinal field measurements from archival optical spectropolarimetric observations of this star. Our analysis of the near-infrared S I lines reveals no evidence of Zeeman broadening, ruling out magnetic field with a strength exceeding 260 G. This null result is compatible with the relative intensification of Fe II lines in the optical spectrum taking into account blending and uncertain atomic parameters of the relevant diagnostic transitions. Longitudinal field measurements at three different nights also yield null results with a precision of 2 G. This study refutes the claims of kG-strength dipolar or tangled magnetic field in o Peg. This star is effectively non-magnetic, with the surface magnetic field characteristics no different from those of other Am stars. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2405.12778v1-abstract-full').style.display = 'none'; document.getElementById('2405.12778v1-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 May, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> May 2024. </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, 8 figures; accepted for publication in A&A</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> A&A 689, A36 (2024) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2404.17517">arXiv:2404.17517</a> <span> [<a href="https://arxiv.org/pdf/2404.17517">pdf</a>, <a href="https://arxiv.org/format/2404.17517">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> </div> </div> <p class="title is-5 mathjax"> Statistical relations between spectropolarimetric observables and the polar strength of the stellar dipolar magnetic field </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Kochukhov%2C+O">O. Kochukhov</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="2404.17517v1-abstract-short" style="display: inline;"> Global magnetic fields of early-type stars are commonly characterised by the mean longitudinal magnetic field $\langle B_{\rm z} \rangle$ and the mean field modulus $\langle B \rangle$, derived from the circular polarisation and intensity spectra, respectively. Observational studies often report a root mean square (rms) of $\langle B_{\rm z} \rangle$ and an average value of $\langle B \rangle$. In… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2404.17517v1-abstract-full').style.display = 'inline'; document.getElementById('2404.17517v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2404.17517v1-abstract-full" style="display: none;"> Global magnetic fields of early-type stars are commonly characterised by the mean longitudinal magnetic field $\langle B_{\rm z} \rangle$ and the mean field modulus $\langle B \rangle$, derived from the circular polarisation and intensity spectra, respectively. Observational studies often report a root mean square (rms) of $\langle B_{\rm z} \rangle$ and an average value of $\langle B \rangle$. In this work, I used numerical simulations to establish statistical relationships between these cumulative magnetic observables and the polar strength, $B_{\rm d}$, of a dipolar magnetic field. I show that in the limit of many measurements randomly distributed in rotational phase, $\langle B_{\rm z} \rangle_{\rm rms}$=$0.179^{+0.031}_{-0.043}$$B_{\rm d}$ and $\langle B \rangle_{\rm avg}$=$0.691^{+0.020}_{-0.023}$$B_{\rm d}$. The same values can be recovered with only three measurements, provided that the observations are distributed uniformly in the rotational phase. These conversion factors are suitable for ensemble analyses of large stellar samples, where each target is covered by a small number of magnetic measurements. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2404.17517v1-abstract-full').style.display = 'none'; document.getElementById('2404.17517v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 26 April, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> April 2024. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">5 pages, 3 figures; accepted for publication in A&A</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2404.12363">arXiv:2404.12363</a> <span> [<a href="https://arxiv.org/pdf/2404.12363">pdf</a>, <a href="https://arxiv.org/format/2404.12363">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Earth and Planetary Astrophysics">astro-ph.EP</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1051/0004-6361/202450438">10.1051/0004-6361/202450438 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> CRIRES$^+$ transmission spectroscopy of WASP-127b. Detection of the resolved signatures of a supersonic equatorial jet and cool poles in a hot planet </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Nortmann%2C+L">L. Nortmann</a>, <a href="/search/astro-ph?searchtype=author&query=Lesjak%2C+F">F. Lesjak</a>, <a href="/search/astro-ph?searchtype=author&query=Yan%2C+F">F. Yan</a>, <a href="/search/astro-ph?searchtype=author&query=Cont%2C+D">D. Cont</a>, <a href="/search/astro-ph?searchtype=author&query=Czesla%2C+S">S. Czesla</a>, <a href="/search/astro-ph?searchtype=author&query=Lavail%2C+A">A. Lavail</a>, <a href="/search/astro-ph?searchtype=author&query=Rains%2C+A+D">A. D. Rains</a>, <a href="/search/astro-ph?searchtype=author&query=Nagel%2C+E">E. Nagel</a>, <a href="/search/astro-ph?searchtype=author&query=Boldt-Christmas%2C+L">L. Boldt-Christmas</a>, <a href="/search/astro-ph?searchtype=author&query=Hatzes%2C+A">A. Hatzes</a>, <a href="/search/astro-ph?searchtype=author&query=Reiners%2C+A">A. Reiners</a>, <a href="/search/astro-ph?searchtype=author&query=Piskunov%2C+N">N. Piskunov</a>, <a href="/search/astro-ph?searchtype=author&query=Kochukhov%2C+O">O. Kochukhov</a>, <a href="/search/astro-ph?searchtype=author&query=Heiter%2C+U">U. Heiter</a>, <a href="/search/astro-ph?searchtype=author&query=Shulyak%2C+D">D. Shulyak</a>, <a href="/search/astro-ph?searchtype=author&query=Rengel%2C+M">M. Rengel</a>, <a href="/search/astro-ph?searchtype=author&query=Seemann%2C+U">U. Seemann</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="2404.12363v2-abstract-short" style="display: inline;"> General circulation models of gas giant exoplanets predict equatorial jets that drive inhomogeneities in the atmospheric physical parameters across the planetary surface. We studied the transmission spectrum of the hot Jupiter WASP-127\,b during one transit in the K band with CRIRES$^+$. Telluric and stellar signals were removed from the data using SYSREM. The planetary signal was investigated usi… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2404.12363v2-abstract-full').style.display = 'inline'; document.getElementById('2404.12363v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2404.12363v2-abstract-full" style="display: none;"> General circulation models of gas giant exoplanets predict equatorial jets that drive inhomogeneities in the atmospheric physical parameters across the planetary surface. We studied the transmission spectrum of the hot Jupiter WASP-127\,b during one transit in the K band with CRIRES$^+$. Telluric and stellar signals were removed from the data using SYSREM. The planetary signal was investigated using the cross-correlation technique. After detecting a spectral signal indicative of atmospheric inhomogeneities, we employed a Bayesian retrieval framework with a 2D modelling approach tailored to address this scenario. We detected strong signals of H$_2$O and CO, which exhibited not one but two distinct cross-correlation peaks. The double-peaked signal can be explained by a supersonic equatorial jet and muted signals at the planetary poles, with the two peaks representing the signals from the planet's morning and evening terminators. We calculated a jet velocity of $7.7\pm0.2$ km~s$^{-1}$ and derive distinct atmospheric properties for the two terminators as well as the polar region. Our retrieval yields a solar C/O ratio and metallicity and challenges previous studies of WASP-127b's atmosphere. It provides tentative evidence for the morning terminator to be cooler than the evening terminator by $-175^{+133}_{-117}$K and shows that the muted signals from the poles can be explained by either significantly lower temperatures or a high cloud deck. The presence of a clear double-peaked signal highlights the importance of taking planetary 3D structure into account during interpretation of atmospheric signals. The supersonic jet velocity and lack of signal from the polar regions, representing a detection of latitudinal inhomogeneity in a spatially unresolved target, showcases the power of high-resolution transmission spectroscopy for the characterisation of global circulation in exoplanet atmospheres. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2404.12363v2-abstract-full').style.display = 'none'; document.getElementById('2404.12363v2-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 November, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 18 April, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> April 2024. </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">20 pages 14 figures, Accepted for publication in Astronomy & Astrophysics (A&A)</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> A&A 693, A213 (2025) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2404.10161">arXiv:2404.10161</a> <span> [<a href="https://arxiv.org/pdf/2404.10161">pdf</a>, <a href="https://arxiv.org/ps/2404.10161">ps</a>, <a href="https://arxiv.org/format/2404.10161">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> </div> </div> <p class="title is-5 mathjax"> Using ZDI maps to determine magnetic forces and torques at the photospheres of Early-type stars </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=MacDonald%2C+J">James MacDonald</a>, <a href="/search/astro-ph?searchtype=author&query=Natan%2C+T">Tali Natan</a>, <a href="/search/astro-ph?searchtype=author&query=Petit%2C+V">V茅ronique Petit</a>, <a href="/search/astro-ph?searchtype=author&query=Kochukhov%2C+O">Oleg Kochukhov</a>, <a href="/search/astro-ph?searchtype=author&query=Shultz%2C+M+E">Matthew E. Shultz</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="2404.10161v1-abstract-short" style="display: inline;"> We use the magnetic field components measured by Zeeman Doppler imaging (ZDI) to calculate the stellar surface force and torque due to magnetic stresses for the fast rotators $蟽$ Ori E, 36 Lyn and CU Vir, and the slow rotator $蟿$ Sco. If we assume the stars have spherical photospheres, the estimated torques give spin down time scales no larger than $7 \times 10^5$ yr. For $蟽$ Ori E, the predicted… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2404.10161v1-abstract-full').style.display = 'inline'; document.getElementById('2404.10161v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2404.10161v1-abstract-full" style="display: none;"> We use the magnetic field components measured by Zeeman Doppler imaging (ZDI) to calculate the stellar surface force and torque due to magnetic stresses for the fast rotators $蟽$ Ori E, 36 Lyn and CU Vir, and the slow rotator $蟿$ Sco. If we assume the stars have spherical photospheres, the estimated torques give spin down time scales no larger than $7 \times 10^5$ yr. For $蟽$ Ori E, the predicted spin down time scale, $\simeq 6000$ yr, is much less than the observationally measured time scale of $\simeq 10^6$ yr. However, for CU Vir, we find that the spin down time scale from its ZDI map is $7 \times 10^5$ yr in good agreement with its average rate of spin down from 1960 to 2010. With the exception of $蟿$ Sco, the net force due to magnetic stresses at the stellar surface are large compared to the surface-integrated pressure. We discuss possible reasons for the large values of the forces (and torques), and suggest that the likely explanation is that rotation and the magnetic stresses create significant departures from spherical symmetry. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2404.10161v1-abstract-full').style.display = 'none'; document.getElementById('2404.10161v1-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 April, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> April 2024. </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">To appear in MNRAS</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2402.01419">arXiv:2402.01419</a> <span> [<a href="https://arxiv.org/pdf/2402.01419">pdf</a>, <a href="https://arxiv.org/format/2402.01419">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> </div> </div> <p class="title is-5 mathjax"> Accretion and magnetism on young eccentric binaries: DQ Tau and AK Sco </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Pouilly%2C+K">Kim Pouilly</a>, <a href="/search/astro-ph?searchtype=author&query=Hahlin%2C+A">Axel Hahlin</a>, <a href="/search/astro-ph?searchtype=author&query=Kochukhov%2C+O">Oleg Kochukhov</a>, <a href="/search/astro-ph?searchtype=author&query=Morin%2C+J">Julien Morin</a>, <a href="/search/astro-ph?searchtype=author&query=K%C3%B3sp%C3%A1l%2C+%C3%81">脕gnes K贸sp谩l</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="2402.01419v1-abstract-short" style="display: inline;"> The accretion and ejection of mass in pre-main sequence (PMS) stars are key processes in stellar evolution as they shape the stellar angular momentum transport necessary for the stars' stability. Magnetospheric accretion onto classical T Tauri stars and low-mass PMS stars has been widely studied in the single-star case. This process can not be directly transferred to PMS binary systems, as tidal a… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2402.01419v1-abstract-full').style.display = 'inline'; document.getElementById('2402.01419v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2402.01419v1-abstract-full" style="display: none;"> The accretion and ejection of mass in pre-main sequence (PMS) stars are key processes in stellar evolution as they shape the stellar angular momentum transport necessary for the stars' stability. Magnetospheric accretion onto classical T Tauri stars and low-mass PMS stars has been widely studied in the single-star case. This process can not be directly transferred to PMS binary systems, as tidal and gravitation effects, and/or accretion from a circumbinary disc (with variable separation of the components in the case of eccentric orbits) are in place. This work examines the accretion process of two PMS eccentric binaries, DQ Tau and AK Sco, using high-resolution spectropolarimetric time series. We investigate how magnetospheric accretion can be applied to these systems by studying the accretion-related emission lines and the magnetic field of each system. We discover that both systems are showing signs of magnetospheric accretion, despite their slightly different configurations, and the weak magnetic field of AK Sco. Furthermore, the magnetic topology of DQ Tau A shows a change relative to the previous orbital cycle studied: previously dominated by the poloidal component, it is now dominated by the toroidal component. We also report an increase of the component's accretion and the absence of an accretion burst at the apastron, suggesting that the component's magnetic variation might be the cause of the inter-cycle variations of the system's accretion. We conclude on the presence of magnetospheric accretion for both systems, together with gravitational effects, especially for AK Sco, composed of more massive components. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2402.01419v1-abstract-full').style.display = 'none'; document.getElementById('2402.01419v1-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> 2 February, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> February 2024. </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">21 pages, 24 figures. Accepted for publication in 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/2402.00721">arXiv:2402.00721</a> <span> [<a href="https://arxiv.org/pdf/2402.00721">pdf</a>, <a href="https://arxiv.org/format/2402.00721">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> </div> </div> <p class="title is-5 mathjax"> Multi-scale magnetic field investigation of the M-dwarf eclipsing binary CU Cancri </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Hahlin%2C+A">A. Hahlin</a>, <a href="/search/astro-ph?searchtype=author&query=Kochukhov%2C+O">O. Kochukhov</a>, <a href="/search/astro-ph?searchtype=author&query=Rains%2C+A+D">A. D. Rains</a>, <a href="/search/astro-ph?searchtype=author&query=Morin%2C+J">J. Morin</a>, <a href="/search/astro-ph?searchtype=author&query=Hussain%2C+G">G. Hussain</a>, <a href="/search/astro-ph?searchtype=author&query=Hebb%2C+L">L. Hebb</a>, <a href="/search/astro-ph?searchtype=author&query=Stassun%2C+K">K. Stassun</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="2402.00721v1-abstract-short" style="display: inline;"> We aim to characterise the magnetic field of the eclipsing binary CU Cnc. The determination of magnetic field parameters of this target enables comparisons with both observations of similar stars and theoretical predictions of the magnetic field strength for CU Cnc. The target is therefore providing an excellent opportunity to test our understanding of the generation of magnetic fields in low-mass… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2402.00721v1-abstract-full').style.display = 'inline'; document.getElementById('2402.00721v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2402.00721v1-abstract-full" style="display: none;"> We aim to characterise the magnetic field of the eclipsing binary CU Cnc. The determination of magnetic field parameters of this target enables comparisons with both observations of similar stars and theoretical predictions of the magnetic field strength for CU Cnc. The target is therefore providing an excellent opportunity to test our understanding of the generation of magnetic fields in low-mass stars and its impact on stellar structure. We use spectropolarimetric observations obtained with ESPaDOnS to investigate the magnetic properties of CU Cnc. We generate average line profiles with LSD, which are used to extract information about the radial velocities of the components, expanding the number of radial velocity measurements available and allowing for a determination of orbital parameters. Stokes V LSD profiles are used with ZDI to obtain large-scale magnetic field structures on both components. We also use polarised radiative transfer modelling to investigate the small-scale fields by utilising Zeeman splitting of magnetically sensitive Ti I lines in non-polarised spectra. The large-scale fields are dominantly poloidal and have an average strength of ~100 G on both components. This analysis of the large-scale fields likely suffers from some amount of hemisphere degeneracy due to the high inclination of the target. Both components also show unusual magnetic field configurations compared to stars with similar parameters, the primary is weakly axisymmetric (~10%) and the secondary has a strong torroidal contribution (~20%). The small-scale fields are significantly stronger, at 3.1 and 3.6 kG for the primary and secondary respectively. This measurement is in excellent agreement with surface field strength predictions for CU Cnc from magnetoconvective stellar evolution models. These results indicates that magnetic fields play a significant role in radius inflation of active stars. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2402.00721v1-abstract-full').style.display = 'none'; document.getElementById('2402.00721v1-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 February, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> February 2024. </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 A&A, 17 pages, 8 figures</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2401.01944">arXiv:2401.01944</a> <span> [<a href="https://arxiv.org/pdf/2401.01944">pdf</a>, <a href="https://arxiv.org/format/2401.01944">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link 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="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/10.3847/2041-8213/ad0a95">10.3847/2041-8213/ad0a95 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Weakened Magnetic Braking in the Exoplanet Host Star 51 Peg </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Metcalfe%2C+T+S">Travis S. Metcalfe</a>, <a href="/search/astro-ph?searchtype=author&query=Strassmeier%2C+K+G">Klaus G. Strassmeier</a>, <a href="/search/astro-ph?searchtype=author&query=Ilyin%2C+I+V">Ilya V. Ilyin</a>, <a href="/search/astro-ph?searchtype=author&query=Buzasi%2C+D">Derek Buzasi</a>, <a href="/search/astro-ph?searchtype=author&query=Kochukhov%2C+O">Oleg Kochukhov</a>, <a href="/search/astro-ph?searchtype=author&query=Ayres%2C+T+R">Thomas R. Ayres</a>, <a href="/search/astro-ph?searchtype=author&query=Basu%2C+S">Sarbani Basu</a>, <a href="/search/astro-ph?searchtype=author&query=Chontos%2C+A">Ashley Chontos</a>, <a href="/search/astro-ph?searchtype=author&query=Finley%2C+A+J">Adam J. Finley</a>, <a href="/search/astro-ph?searchtype=author&query=See%2C+V">Victor See</a>, <a href="/search/astro-ph?searchtype=author&query=Stassun%2C+K+G">Keivan G. Stassun</a>, <a href="/search/astro-ph?searchtype=author&query=van+Saders%2C+J+L">Jennifer L. van Saders</a>, <a href="/search/astro-ph?searchtype=author&query=Sepulveda%2C+A+G">Aldo G. Sepulveda</a>, <a href="/search/astro-ph?searchtype=author&query=Ricker%2C+G+R">George R. Ricker</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="2401.01944v1-abstract-short" style="display: inline;"> The consistently low activity level of the old solar analog 51 Peg not only facilitated the discovery of the first hot Jupiter, but also led to the suggestion that the star could be experiencing a magnetic grand minimum. However, the 50 year time series showing minimal chromospheric variability could also be associated with the onset of weakened magnetic braking (WMB), where sufficiently slow rota… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2401.01944v1-abstract-full').style.display = 'inline'; document.getElementById('2401.01944v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2401.01944v1-abstract-full" style="display: none;"> The consistently low activity level of the old solar analog 51 Peg not only facilitated the discovery of the first hot Jupiter, but also led to the suggestion that the star could be experiencing a magnetic grand minimum. However, the 50 year time series showing minimal chromospheric variability could also be associated with the onset of weakened magnetic braking (WMB), where sufficiently slow rotation disrupts cycling activity and the production of large-scale magnetic fields by the stellar dynamo, thereby shrinking the Alfven radius and inhibiting the efficient loss of angular momentum to magnetized stellar winds. In this Letter, we evaluate the magnetic evolutionary state of 51 Peg by estimating its wind braking torque. We use new spectropolarimetric measurements from the Large Binocular Telescope to reconstruct the large-scale magnetic morphology, we reanalyze archival X-ray measurements to estimate the mass-loss rate, and we detect solar-like oscillations in photometry from the Transiting Exoplanet Survey Satellite, yielding precise stellar properties from asteroseismology. Our estimate of the wind braking torque for 51 Peg clearly places it in the WMB regime, driven by changes in the mass-loss rate and the magnetic field strength and morphology that substantially exceed theoretical expectations. Although our revised stellar properties have minimal consequences for the characterization of the exoplanet, they have interesting implications for the current space weather environment of the system. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2401.01944v1-abstract-full').style.display = 'none'; document.getElementById('2401.01944v1-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 January, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> January 2024. </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">ApJ Letters (accepted), 6 pages including 4 figures and 1 table. Data available at https://doi.org/10.5281/zenodo.8381444</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Astrophys. J. 960, L6 (2024) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2312.08320">arXiv:2312.08320</a> <span> [<a href="https://arxiv.org/pdf/2312.08320">pdf</a>, <a href="https://arxiv.org/format/2312.08320">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Earth and Planetary Astrophysics">astro-ph.EP</span> </div> </div> <p class="title is-5 mathjax"> Optimising spectroscopic observations of transiting exoplanets </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Boldt-Christmas%2C+L">Linn Boldt-Christmas</a>, <a href="/search/astro-ph?searchtype=author&query=Lesjak%2C+F">Fabio Lesjak</a>, <a href="/search/astro-ph?searchtype=author&query=Wehrhahn%2C+A">Ansgar Wehrhahn</a>, <a href="/search/astro-ph?searchtype=author&query=Piskunov%2C+N">Nikolai Piskunov</a>, <a href="/search/astro-ph?searchtype=author&query=Rains%2C+A+D">Adam D. Rains</a>, <a href="/search/astro-ph?searchtype=author&query=Nortmann%2C+L">Lisa Nortmann</a>, <a href="/search/astro-ph?searchtype=author&query=Kochukhov%2C+O">Oleg Kochukhov</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="2312.08320v1-abstract-short" style="display: inline;"> When observing the atmospheres of transiting exoplanets using high-resolution spectroscopy, one aims to detect well-resolved spectral features with high signal-to-noise ratios (SNR) as is possible today with modern spectrographs. However, obtaining such high-quality observations comes with a trade-off: a lower cadence of fewer, longer exposures across the transit collects more photons thanks to re… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2312.08320v1-abstract-full').style.display = 'inline'; document.getElementById('2312.08320v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2312.08320v1-abstract-full" style="display: none;"> When observing the atmospheres of transiting exoplanets using high-resolution spectroscopy, one aims to detect well-resolved spectral features with high signal-to-noise ratios (SNR) as is possible today with modern spectrographs. However, obtaining such high-quality observations comes with a trade-off: a lower cadence of fewer, longer exposures across the transit collects more photons thanks to reduced overheads, enhancing the SNR of each observation, while a higher cadence of several, shorter exposures minimises spectral feature smearing due to the continuously changing radial velocity of the planet. Considering that maximising SNR and minimising smearing are both beneficial to analysis, there is a need to establish where the optimal compromise lies. In this work, we model real transit events based on targets as they would be observed with VLT/CRIRES+ at Paranal Observatory. Creating four hypothetical scenarios, we simulate each observation across 100 realisations of the same transit event in order to vary the time resolution only. We remove telluric and stellar lines using the SYSREM algorithm and analyse them through cross-correlation with model templates, measuring how successfully each time resolution and case detects the planetary signal. We demonstrate that there is a continuous change in the detection significance based on time resolutions, and that the function of this significance has clear maxima. The strength and location of this maxima varies on e.g. planet system parameters, instrumentation, and no. of removal iterations. We discuss why observers should therefore take several factors into account, using a strategy akin to the 'exposure triangle' from traditional photography where a balance must be struck by considering the full context of the observation. Our method is robust and may be employed by observers to estimate best observational strategies for other targets. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2312.08320v1-abstract-full').style.display = 'none'; document.getElementById('2312.08320v1-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 December, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> December 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">16 pages, 8 figures, 2 tables. Accepted 13 Dec 2023 for publication in A&A</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2312.04247">arXiv:2312.04247</a> <span> [<a href="https://arxiv.org/pdf/2312.04247">pdf</a>, <a href="https://arxiv.org/format/2312.04247">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> </div> </div> <p class="title is-5 mathjax"> The large-scale magnetic field of the M dwarf double-line spectroscopic binary FK Aqr </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Tsvetkova%2C+S">S. Tsvetkova</a>, <a href="/search/astro-ph?searchtype=author&query=Morin%2C+J">J. Morin</a>, <a href="/search/astro-ph?searchtype=author&query=Folsom%2C+C+P">C. P. Folsom</a>, <a href="/search/astro-ph?searchtype=author&query=Bouquin%2C+J+-+L">J. -B. Le Bouquin</a>, <a href="/search/astro-ph?searchtype=author&query=Alecian%2C+E">E. Alecian</a>, <a href="/search/astro-ph?searchtype=author&query=Bellotti%2C+S">S. Bellotti</a>, <a href="/search/astro-ph?searchtype=author&query=Hussain%2C+G">G. Hussain</a>, <a href="/search/astro-ph?searchtype=author&query=Kochukhov%2C+O">O. Kochukhov</a>, <a href="/search/astro-ph?searchtype=author&query=Marsden%2C+S+C">S. C. Marsden</a>, <a href="/search/astro-ph?searchtype=author&query=Neiner%2C+C">C. Neiner</a>, <a href="/search/astro-ph?searchtype=author&query=Petit%2C+P">P. Petit</a>, <a href="/search/astro-ph?searchtype=author&query=Wade%2C+G+A">G. A. Wade</a>, <a href="/search/astro-ph?searchtype=author&query=collaboration%2C+t+B">the BinaMIcS collaboration</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="2312.04247v1-abstract-short" style="display: inline;"> This work is part of the BinaMIcS project, the aim of which is to understand the interaction between binarity and magnetism in close binary systems. All the studied spectroscopic binaries targeted by the BinaMIcS project encompass hot massive and intermediate-mass stars on the main sequence, as well as cool stars over a wide range of evolutionary stages. The present paper focuses on the binary sys… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2312.04247v1-abstract-full').style.display = 'inline'; document.getElementById('2312.04247v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2312.04247v1-abstract-full" style="display: none;"> This work is part of the BinaMIcS project, the aim of which is to understand the interaction between binarity and magnetism in close binary systems. All the studied spectroscopic binaries targeted by the BinaMIcS project encompass hot massive and intermediate-mass stars on the main sequence, as well as cool stars over a wide range of evolutionary stages. The present paper focuses on the binary system FK Aqr, which is composed of two early M dwarfs. Both stars are already known to be magnetically active based on their light curves and detected flare activity. In addition, the two components have large convective envelopes with masses just above the fully convective limit, making the system an ideal target for studying effect of binarity on stellar dynamos. We use spectropolarimetric observations obtained with ESPaDOnS at CFHT in September 2014. Mean Stokes I and V line profiles are extracted using the least-squares deconvolution (LSD) method. The radial velocities of the two components are measured from the LSD Stokes I profiles and are combined with interferometric measurements in order to constrain the orbital parameters of the system. The longitudinal magnetic fields Bl and chromospheric activity indicators are measured from the LSD mean line profiles. The rotational modulation of the Stokes V profiles is used to reconstruct the surface magnetic field structures of both stars via the Zeeman Doppler imaging (ZDI) inversion technique. Maps of the surface magnetic field structures of both components of FK Aqr are presented for the first time. Our study shows that both components host similar large-scale magnetic fields of moderate intensity (Bmean ~ 0.25 kG); both are predominantly poloidal and feature a strong axisymmetric dipolar component. (abridged) <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2312.04247v1-abstract-full').style.display = 'none'; document.getElementById('2312.04247v1-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> 7 December, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> December 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">19 pages, 6 figures, 6 tables + appendices, accepted for publication in A&A, in press</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2312.04199">arXiv:2312.04199</a> <span> [<a href="https://arxiv.org/pdf/2312.04199">pdf</a>, <a href="https://arxiv.org/ps/2312.04199">ps</a>, <a href="https://arxiv.org/format/2312.04199">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> </div> </div> <p class="title is-5 mathjax"> TESS Cycle 2 observations of roAp stars with 2-min cadence data </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Holdsworth%2C+D+L">D. L. Holdsworth</a>, <a href="/search/astro-ph?searchtype=author&query=Cunha%2C+M+S">M. S. Cunha</a>, <a href="/search/astro-ph?searchtype=author&query=Lares-Martiz%2C+M">M. Lares-Martiz</a>, <a href="/search/astro-ph?searchtype=author&query=Kurtz%2C+D+W">D. W. Kurtz</a>, <a href="/search/astro-ph?searchtype=author&query=Antoci%2C+V">V. Antoci</a>, <a href="/search/astro-ph?searchtype=author&query=Forteza%2C+S+B">S. Barcel贸 Forteza</a>, <a href="/search/astro-ph?searchtype=author&query=De+Cat%2C+P">P. De Cat</a>, <a href="/search/astro-ph?searchtype=author&query=Derekas%2C+A">A. Derekas</a>, <a href="/search/astro-ph?searchtype=author&query=Kayhan%2C+C">C. Kayhan</a>, <a href="/search/astro-ph?searchtype=author&query=Ozuyar%2C+D">D. Ozuyar</a>, <a href="/search/astro-ph?searchtype=author&query=Skarka%2C+M">M. Skarka</a>, <a href="/search/astro-ph?searchtype=author&query=Hey%2C+D+R">D. R. Hey</a>, <a href="/search/astro-ph?searchtype=author&query=Shi%2C+F">F. Shi</a>, <a href="/search/astro-ph?searchtype=author&query=Bowman%2C+D+M">D. M. Bowman</a>, <a href="/search/astro-ph?searchtype=author&query=Kobzar%2C+O">O. Kobzar</a>, <a href="/search/astro-ph?searchtype=author&query=G%C3%B3mez%2C+A+A">A. Ayala G贸mez</a>, <a href="/search/astro-ph?searchtype=author&query=Bogn%C3%A1r%2C+Z">Zs. Bogn谩r</a>, <a href="/search/astro-ph?searchtype=author&query=Buzasi%2C+D+L">D. L. Buzasi</a>, <a href="/search/astro-ph?searchtype=author&query=Ebadi%2C+M">M. Ebadi</a>, <a href="/search/astro-ph?searchtype=author&query=Fox-Machado%2C+L">L. Fox-Machado</a>, <a href="/search/astro-ph?searchtype=author&query=Hern%C3%A1ndez%2C+A+G">A. Garc铆a Hern谩ndez</a>, <a href="/search/astro-ph?searchtype=author&query=Ghasemi%2C+H">H. Ghasemi</a>, <a href="/search/astro-ph?searchtype=author&query=Guzik%2C+J+A">J. A. Guzik</a>, <a href="/search/astro-ph?searchtype=author&query=Handberg%2C+R">R. Handberg</a>, <a href="/search/astro-ph?searchtype=author&query=Handler%2C+G">G. Handler</a> , et al. (24 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="2312.04199v1-abstract-short" style="display: inline;"> We present the results of a systematic search of the Transiting Exoplanet Survey Satellite (TESS) 2-min cadence data for new rapidly oscillating Ap (roAp) stars observed during the Cycle 2 phase of its mission. We find seven new roAp stars previously unreported as such and present the analysis of a further 25 roAp stars that are already known. Three of the new stars show multiperiodic pulsations,… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2312.04199v1-abstract-full').style.display = 'inline'; document.getElementById('2312.04199v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2312.04199v1-abstract-full" style="display: none;"> We present the results of a systematic search of the Transiting Exoplanet Survey Satellite (TESS) 2-min cadence data for new rapidly oscillating Ap (roAp) stars observed during the Cycle 2 phase of its mission. We find seven new roAp stars previously unreported as such and present the analysis of a further 25 roAp stars that are already known. Three of the new stars show multiperiodic pulsations, while all new members are rotationally variable stars, leading to almost 70 per cent (22) of the roAp stars presented being $伪^2$ CVn-type variable stars. We show that targeted observations of known chemically peculiar stars are likely to overlook many new roAp stars, and demonstrate that multi-epoch observations are necessary to see pulsational behaviour changes. We find a lack of roAp stars close to the blue edge of the theoretical roAp instability strip, and reaffirm that mode instability is observed more frequently with precise, space-based observations. In addition to the Cycle 2 observations, we analyse TESS data for all known roAp stars. This amounts to 18 further roAp stars observed by TESS. Finally, we list six known roAp stars that TESS is yet to observe. We deduce that the incidence of roAp stars amongst the Ap star population is just 5.5 per cent, raising fundamental questions about the conditions required to excite pulsations in Ap stars. This work, coupled with our previous work on roAp stars in Cycle 1 observations, presents the most comprehensive, homogeneous study of the roAp stars in the TESS nominal mission, with a collection of 112 confirmed roAp stars in total. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2312.04199v1-abstract-full').style.display = 'none'; document.getElementById('2312.04199v1-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> 7 December, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> December 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 for publication in MNRAS. 32 Pages, 2 Tables, 77 Figures</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2312.04136">arXiv:2312.04136</a> <span> [<a href="https://arxiv.org/pdf/2312.04136">pdf</a>, <a href="https://arxiv.org/format/2312.04136">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> </div> </div> <p class="title is-5 mathjax"> Surface distribution of small-scale magnetic field on the active cool star LQ Hydrae </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Kochukhov%2C+O">O. Kochukhov</a>, <a href="/search/astro-ph?searchtype=author&query=Hackman%2C+T">T. Hackman</a>, <a href="/search/astro-ph?searchtype=author&query=Lehtinen%2C+J+J">J. J. Lehtinen</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="2312.04136v1-abstract-short" style="display: inline;"> It is well known that small-scale magnetism dominates the surface magnetic field topologies of active late-type stars. However, little information is available on the spatial distribution of this key magnetic field component. Here, we take advantage of the recently developed magnetic field diagnostic procedure relying on the magnetic intensification of iron atomic lines in the optical. We extend t… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2312.04136v1-abstract-full').style.display = 'inline'; document.getElementById('2312.04136v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2312.04136v1-abstract-full" style="display: none;"> It is well known that small-scale magnetism dominates the surface magnetic field topologies of active late-type stars. However, little information is available on the spatial distribution of this key magnetic field component. Here, we take advantage of the recently developed magnetic field diagnostic procedure relying on the magnetic intensification of iron atomic lines in the optical. We extend this methodology from measuring a single average field strength value to simultaneous Doppler imaging reconstruction of the two-dimensional maps of temperature and magnetic field strength. We applied this novel surface mapping approach to two spectroscopic data sets of the young active Sun-like star LQ Hya. For both epochs, we found a fairly uniform field strength distribution, apart from a latitudinal trend of the field strength increasing from 1.5-2.0 kG at low latitudes to 3.0-3.5 kG, close to the rotational poles. This distribution of the small-scale field does not display a clear correlation with the locations of temperature spots or the global magnetic field structure reconstructed for the same epochs. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2312.04136v1-abstract-full').style.display = 'none'; document.getElementById('2312.04136v1-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> 7 December, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> December 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">7 pages, 6 figures; accepted for publication in A&A</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2310.14865">arXiv:2310.14865</a> <span> [<a href="https://arxiv.org/pdf/2310.14865">pdf</a>, <a href="https://arxiv.org/format/2310.14865">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> </div> </div> <p class="title is-5 mathjax"> First Chromospheric Activity and Doppler Imaging Study of PW And Using a New Doppler Imaging Code: SpotDIPy </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Bahar%2C+E">Engin Bahar</a>, <a href="/search/astro-ph?searchtype=author&query=%C5%9Eenavc%C4%B1%2C+H+V">Hakan V. 艦enavc谋</a>, <a href="/search/astro-ph?searchtype=author&query=I%C5%9F%C4%B1k%2C+E">Emre I艧谋k</a>, <a href="/search/astro-ph?searchtype=author&query=Hussain%2C+G+A+J">Gaitee A. J. Hussain</a>, <a href="/search/astro-ph?searchtype=author&query=Kochukhov%2C+O">Oleg Kochukhov</a>, <a href="/search/astro-ph?searchtype=author&query=Montes%2C+D">David Montes</a>, <a href="/search/astro-ph?searchtype=author&query=Xiang%2C+Y">Yue Xiang</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="2310.14865v1-abstract-short" style="display: inline;"> Measuring coverage of dark spots on cool stars is important in understanding how stellar magnetic activity scales with the rotation rate and convection zone depth. In this respect, it is crucial to infer surface magnetic patterns on G and K stars, to reveal solar-like stellar dynamos in action. Molecular bands serve as invaluable indicators of cool spots on the surfaces of stars, as they play a cr… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2310.14865v1-abstract-full').style.display = 'inline'; document.getElementById('2310.14865v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2310.14865v1-abstract-full" style="display: none;"> Measuring coverage of dark spots on cool stars is important in understanding how stellar magnetic activity scales with the rotation rate and convection zone depth. In this respect, it is crucial to infer surface magnetic patterns on G and K stars, to reveal solar-like stellar dynamos in action. Molecular bands serve as invaluable indicators of cool spots on the surfaces of stars, as they play a crucial role in enabling accurate assessments of the extent of spot coverage across the stellar surface. Therefore, more reliable surface images can be obtained considering the inversion of atomic lines with molecular bands. In this context, we simultaneously carry out Doppler imaging (DI) using atomic lines as well as Titanium Oxide (TiO) band profiles of PW And (K2 V) and also investigate chromospheric activity indicators for the first time in the literature, using the high-resolution spectra. The surface spot distribution obtained from the inversion process represents both atomic line and TiO-band profiles quite accurately. The chromospheric emission is also correlated with photospheric spot coverage, except during a possible flare event during the observations. We detect frequent flare activity, using TESS photometry. We also introduce a new open-source, Python-based DI code SpotDIPy that allows performing surface reconstructions of single stars using the maximum entropy method. We test the code by comparing surface reconstruction simulations with the extensively used DoTS code. We show that the surface brightness distribution maps reconstructed via both codes using the same simulated data are consistent with each other. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2310.14865v1-abstract-full').style.display = 'none'; document.getElementById('2310.14865v1-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 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">Accepted for publication by 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/2308.09808">arXiv:2308.09808</a> <span> [<a href="https://arxiv.org/pdf/2308.09808">pdf</a>, <a href="https://arxiv.org/format/2308.09808">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> </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/10.3847/1538-3881/acf1f7">10.3847/1538-3881/acf1f7 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Asteroseismology and Spectropolarimetry of the Exoplanet Host Star $位$ Serpentis </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Metcalfe%2C+T+S">Travis S. Metcalfe</a>, <a href="/search/astro-ph?searchtype=author&query=Buzasi%2C+D">Derek Buzasi</a>, <a href="/search/astro-ph?searchtype=author&query=Huber%2C+D">Daniel Huber</a>, <a href="/search/astro-ph?searchtype=author&query=Pinsonneault%2C+M+H">Marc H. Pinsonneault</a>, <a href="/search/astro-ph?searchtype=author&query=van+Saders%2C+J+L">Jennifer L. van Saders</a>, <a href="/search/astro-ph?searchtype=author&query=Ayres%2C+T+R">Thomas R. Ayres</a>, <a href="/search/astro-ph?searchtype=author&query=Basu%2C+S">Sarbani Basu</a>, <a href="/search/astro-ph?searchtype=author&query=Drake%2C+J+J">Jeremy J. Drake</a>, <a href="/search/astro-ph?searchtype=author&query=Egeland%2C+R">Ricky Egeland</a>, <a href="/search/astro-ph?searchtype=author&query=Kochukhov%2C+O">Oleg Kochukhov</a>, <a href="/search/astro-ph?searchtype=author&query=Petit%2C+P">Pascal Petit</a>, <a href="/search/astro-ph?searchtype=author&query=Saar%2C+S+H">Steven H. Saar</a>, <a href="/search/astro-ph?searchtype=author&query=See%2C+V">Victor See</a>, <a href="/search/astro-ph?searchtype=author&query=Stassun%2C+K+G">Keivan G. Stassun</a>, <a href="/search/astro-ph?searchtype=author&query=Li%2C+Y">Yaguang Li</a>, <a href="/search/astro-ph?searchtype=author&query=Bedding%2C+T+R">Timothy R. Bedding</a>, <a href="/search/astro-ph?searchtype=author&query=Breton%2C+S+N">Sylvain N. Breton</a>, <a href="/search/astro-ph?searchtype=author&query=Finley%2C+A+J">Adam J. Finley</a>, <a href="/search/astro-ph?searchtype=author&query=Garcia%2C+R+A">Rafael A. Garcia</a>, <a href="/search/astro-ph?searchtype=author&query=Kjeldsen%2C+H">Hans Kjeldsen</a>, <a href="/search/astro-ph?searchtype=author&query=Nielsen%2C+M+B">Martin B. Nielsen</a>, <a href="/search/astro-ph?searchtype=author&query=Ong%2C+J+M+J">J. M. Joel Ong</a>, <a href="/search/astro-ph?searchtype=author&query=Rorsted%2C+J+L">Jakob L. Rorsted</a>, <a href="/search/astro-ph?searchtype=author&query=Stokholm%2C+A">Amalie Stokholm</a>, <a href="/search/astro-ph?searchtype=author&query=Winther%2C+M+L">Mark L. Winther</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="2308.09808v1-abstract-short" style="display: inline;"> The bright star $位$ Ser hosts a hot Neptune with a minimum mass of 13.6 $M_\oplus$ and a 15.5 day orbit. It also appears to be a solar analog, with a mean rotation period of 25.8 days and surface differential rotation very similar to the Sun. We aim to characterize the fundamental properties of this system, and to constrain the evolutionary pathway that led to its present configuration. We detect… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2308.09808v1-abstract-full').style.display = 'inline'; document.getElementById('2308.09808v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2308.09808v1-abstract-full" style="display: none;"> The bright star $位$ Ser hosts a hot Neptune with a minimum mass of 13.6 $M_\oplus$ and a 15.5 day orbit. It also appears to be a solar analog, with a mean rotation period of 25.8 days and surface differential rotation very similar to the Sun. We aim to characterize the fundamental properties of this system, and to constrain the evolutionary pathway that led to its present configuration. We detect solar-like oscillations in time series photometry from the Transiting Exoplanet Survey Satellite (TESS), and we derive precise asteroseismic properties from detailed modeling. We obtain new spectropolarimetric data, and we use them to reconstruct the large-scale magnetic field morphology. We reanalyze the complete time series of chromospheric activity measurements from the Mount Wilson Observatory, and we present new X-ray and ultraviolet observations from the Chandra and Hubble space telescopes. Finally, we use the updated observational constraints to assess the rotational history of the star and to estimate the wind braking torque. We conclude that the remaining uncertainty on stellar age currently prevents an unambiguous interpretation of the properties of $位$ Ser, and that the rate of angular momentum loss appears to be higher than for other stars with similar Rossby number. Future asteroseismic observations may help to improve the precision of the stellar age. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2308.09808v1-abstract-full').style.display = 'none'; document.getElementById('2308.09808v1-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 August, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> August 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">19 pages including 9 figures and 6 tables. Astronomical Journal, accepted</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Astron. J. 166, 167 (2023) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2307.11627">arXiv:2307.11627</a> <span> [<a href="https://arxiv.org/pdf/2307.11627">pdf</a>, <a href="https://arxiv.org/format/2307.11627">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Earth and Planetary Astrophysics">astro-ph.EP</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/10.1051/0004-6361/202347151">10.1051/0004-6361/202347151 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Retrieval of the dayside atmosphere of WASP-43b with CRIRES+ </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Lesjak%2C+F">F. Lesjak</a>, <a href="/search/astro-ph?searchtype=author&query=Nortmann%2C+L">L. Nortmann</a>, <a href="/search/astro-ph?searchtype=author&query=Yan%2C+F">F. Yan</a>, <a href="/search/astro-ph?searchtype=author&query=Cont%2C+D">D. Cont</a>, <a href="/search/astro-ph?searchtype=author&query=Reiners%2C+A">A. Reiners</a>, <a href="/search/astro-ph?searchtype=author&query=Piskunov%2C+N">N. Piskunov</a>, <a href="/search/astro-ph?searchtype=author&query=Hatzes%2C+A">A. Hatzes</a>, <a href="/search/astro-ph?searchtype=author&query=Boldt-Christmas%2C+L">L. Boldt-Christmas</a>, <a href="/search/astro-ph?searchtype=author&query=Czesla%2C+S">S. Czesla</a>, <a href="/search/astro-ph?searchtype=author&query=Heiter%2C+U">U. Heiter</a>, <a href="/search/astro-ph?searchtype=author&query=Kochukhov%2C+O">O. Kochukhov</a>, <a href="/search/astro-ph?searchtype=author&query=Lavail%2C+A">A. Lavail</a>, <a href="/search/astro-ph?searchtype=author&query=Nagel%2C+E">E. Nagel</a>, <a href="/search/astro-ph?searchtype=author&query=Rains%2C+A+D">A. D. Rains</a>, <a href="/search/astro-ph?searchtype=author&query=Rengel%2C+M">M. Rengel</a>, <a href="/search/astro-ph?searchtype=author&query=Rodler%2C+F">F. Rodler</a>, <a href="/search/astro-ph?searchtype=author&query=Seemann%2C+U">U. Seemann</a>, <a href="/search/astro-ph?searchtype=author&query=Shulyak%2C+D">D. Shulyak</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="2307.11627v1-abstract-short" style="display: inline;"> Accurately estimating the C/O ratio of hot Jupiter atmospheres is a promising pathway towards understanding planet formation and migration, as well as the formation of clouds and the overall atmospheric composition. The atmosphere of the hot Jupiter WASP-43b has been extensively analysed using low-resolution observations with HST and Spitzer, but these previous observations did not cover the K ban… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2307.11627v1-abstract-full').style.display = 'inline'; document.getElementById('2307.11627v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2307.11627v1-abstract-full" style="display: none;"> Accurately estimating the C/O ratio of hot Jupiter atmospheres is a promising pathway towards understanding planet formation and migration, as well as the formation of clouds and the overall atmospheric composition. The atmosphere of the hot Jupiter WASP-43b has been extensively analysed using low-resolution observations with HST and Spitzer, but these previous observations did not cover the K band, which hosts prominent spectral features of major carbon-bearing species such as CO and CH$_{4}$. As a result, the ability to establish precise constraints on the C/O ratio was limited. Moreover, the planet has not been studied at high spectral resolution, which can provide insights into the atmospheric dynamics. In this study, we present the first high-resolution dayside spectra of WASP-43b with the new CRIRES$^+$ spectrograph. By observing the planet in the K band, we successfully detected the presence of CO and provide evidence for the existence of H$_2$O using the cross-correlation method. This discovery represents the first direct detection of CO in the atmosphere of WASP-43b. Furthermore, we retrieved the temperature-pressure profile, abundances of CO and H$_2$O, and a super-solar C/O ratio of 0.78 by applying a Bayesian retrieval framework to the data. Our findings also shed light on the atmospheric characteristics of WASP-43b. We found no evidence for a cloud deck on the dayside, and recovered a line broadening indicative of an equatorial super-rotation corresponding to a jet with a wind speed of $\sim$ 5 km s$^{-1}$, matching the results of previous forward models and low-resolution atmospheric retrievals for this planet. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2307.11627v1-abstract-full').style.display = 'none'; document.getElementById('2307.11627v1-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, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> July 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">15 pages, 14 figures</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> A&A 678, A23 (2023) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2307.09181">arXiv:2307.09181</a> <span> [<a href="https://arxiv.org/pdf/2307.09181">pdf</a>, <a href="https://arxiv.org/format/2307.09181">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Earth and Planetary Astrophysics">astro-ph.EP</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/ace0c7">10.3847/2041-8213/ace0c7 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Company for the ultra-high density, ultra-short period sub-Earth GJ 367 b: discovery of two additional low-mass planets at 11.5 and 34 days </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Goffo%2C+E">Elisa Goffo</a>, <a href="/search/astro-ph?searchtype=author&query=Gandolfi%2C+D">Davide Gandolfi</a>, <a href="/search/astro-ph?searchtype=author&query=Egger%2C+J+A">Jo Ann Egger</a>, <a href="/search/astro-ph?searchtype=author&query=Mustill%2C+A+J">Alexander J. Mustill</a>, <a href="/search/astro-ph?searchtype=author&query=Albrecht%2C+S+H">Simon H. Albrecht</a>, <a href="/search/astro-ph?searchtype=author&query=Hirano%2C+T">Teruyuki Hirano</a>, <a href="/search/astro-ph?searchtype=author&query=Kochukhov%2C+O">Oleg Kochukhov</a>, <a href="/search/astro-ph?searchtype=author&query=Astudillo-Defru%2C+N">Nicola Astudillo-Defru</a>, <a href="/search/astro-ph?searchtype=author&query=Barragan%2C+O">Oscar Barragan</a>, <a href="/search/astro-ph?searchtype=author&query=Serrano%2C+L+M">Luisa M. Serrano</a>, <a href="/search/astro-ph?searchtype=author&query=Hatzes%2C+A+P">Artie P. Hatzes</a>, <a href="/search/astro-ph?searchtype=author&query=Alibert%2C+Y">Yann Alibert</a>, <a href="/search/astro-ph?searchtype=author&query=Guenther%2C+E">Eike Guenther</a>, <a href="/search/astro-ph?searchtype=author&query=Dai%2C+F">Fei Dai</a>, <a href="/search/astro-ph?searchtype=author&query=Lam%2C+K+W+F">Kristine W. F. Lam</a>, <a href="/search/astro-ph?searchtype=author&query=Csizmadia%2C+S">Szil谩rd Csizmadia</a>, <a href="/search/astro-ph?searchtype=author&query=Smith%2C+A+M+S">Alexis M. S. Smith</a>, <a href="/search/astro-ph?searchtype=author&query=Fossati%2C+L">Luca Fossati</a>, <a href="/search/astro-ph?searchtype=author&query=Luque%2C+R">Rafael Luque</a>, <a href="/search/astro-ph?searchtype=author&query=Rodler%2C+F">Florian Rodler</a>, <a href="/search/astro-ph?searchtype=author&query=Winther%2C+M+L">Mark L. Winther</a>, <a href="/search/astro-ph?searchtype=author&query=R%C3%B8rsted%2C+J+L">Jakob L. R酶rsted</a>, <a href="/search/astro-ph?searchtype=author&query=Alarcon%2C+J">Javier Alarcon</a>, <a href="/search/astro-ph?searchtype=author&query=Bonfils%2C+X">Xavier Bonfils</a>, <a href="/search/astro-ph?searchtype=author&query=Cochran%2C+W+D">William D. Cochran</a> , et al. (16 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="2307.09181v1-abstract-short" style="display: inline;"> GJ 367 is a bright (V $\approx$ 10.2) M1 V star that has been recently found to host a transiting ultra-short period sub-Earth on a 7.7 hr orbit. With the aim of improving the planetary mass and radius and unveiling the inner architecture of the system, we performed an intensive radial velocity follow-up campaign with the HARPS spectrograph -- collecting 371 high-precision measurements over a base… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2307.09181v1-abstract-full').style.display = 'inline'; document.getElementById('2307.09181v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2307.09181v1-abstract-full" style="display: none;"> GJ 367 is a bright (V $\approx$ 10.2) M1 V star that has been recently found to host a transiting ultra-short period sub-Earth on a 7.7 hr orbit. With the aim of improving the planetary mass and radius and unveiling the inner architecture of the system, we performed an intensive radial velocity follow-up campaign with the HARPS spectrograph -- collecting 371 high-precision measurements over a baseline of nearly 3 years -- and combined our Doppler measurements with new TESS observations from sectors 35 and 36. We found that GJ 367 b has a mass of $M_\mathrm{b}$ = 0.633 $\pm$ 0.050 M$_{\oplus}$ and a radius of $R_\mathrm{b}$ = 0.699 $\pm$ 0.024 R$_{\oplus}$, corresponding to precisions of 8% and 3.4%, respectively. This implies a planetary bulk density of $蟻_\mathrm{b}$ = 10.2 $\pm$ 1.3 g cm$^{-3}$, i.e., 85% higher than Earth's density. We revealed the presence of two additional non transiting low-mass companions with orbital periods of $\sim$11.5 and 34 days and minimum masses of $M_\mathrm{c}\sin{i_\mathrm{c}}$ = 4.13 $\pm$ 0.36 M$_{\oplus}$ and $M_\mathrm{d}\sin{i_\mathrm{d}}$ = 6.03 $\pm$ 0.49 M$_{\oplus}$, respectively, which lie close to the 3:1 mean motion commensurability. GJ 367 b joins the small class of high-density planets, namely the class of super-Mercuries, being the densest ultra-short period small planet known to date. Thanks to our precise mass and radius estimates, we explored the potential internal composition and structure of GJ 367 b, and found that it is expected to have an iron core with a mass fraction of 0.91$^{+0.07}_{-0.23}$. How this iron core is formed and how such a high density is reached is still not clear, and we discuss the possible pathways of formation of such a small ultra-dense planet. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2307.09181v1-abstract-full').style.display = 'none'; document.getElementById('2307.09181v1-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 July, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> July 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">28 pages, 11 figures. Accepted for publication in ApJL</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> ApJL 955 L3 (2023) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2307.01016">arXiv:2307.01016</a> <span> [<a href="https://arxiv.org/pdf/2307.01016">pdf</a>, <a href="https://arxiv.org/format/2307.01016">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> </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/10.1051/0004-6361/202346845">10.1051/0004-6361/202346845 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Monitoring the large-scale magnetic field of AD~Leo with SPIRou, ESPaDOnS and Narval. Toward a magnetic polarity reversal? </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Bellotti%2C+S">S. Bellotti</a>, <a href="/search/astro-ph?searchtype=author&query=Morin%2C+J">J. Morin</a>, <a href="/search/astro-ph?searchtype=author&query=Lehmann%2C+L+T">L. T. Lehmann</a>, <a href="/search/astro-ph?searchtype=author&query=Folsom%2C+C+P">C. P. Folsom</a>, <a href="/search/astro-ph?searchtype=author&query=Hussain%2C+G+A+J">G. A. J. Hussain</a>, <a href="/search/astro-ph?searchtype=author&query=Petit%2C+P">P. Petit</a>, <a href="/search/astro-ph?searchtype=author&query=Donati%2C+J+F">J. F. Donati</a>, <a href="/search/astro-ph?searchtype=author&query=Lavail%2C+A">A. Lavail</a>, <a href="/search/astro-ph?searchtype=author&query=Carmona%2C+A">A. Carmona</a>, <a href="/search/astro-ph?searchtype=author&query=Martioli%2C+E">E. Martioli</a>, <a href="/search/astro-ph?searchtype=author&query=Zaire%2C+B+R">B. Romano Zaire</a>, <a href="/search/astro-ph?searchtype=author&query=Alecian%2C+E">E. Alecian</a>, <a href="/search/astro-ph?searchtype=author&query=Moutou%2C+C">C. Moutou</a>, <a href="/search/astro-ph?searchtype=author&query=Fouque%2C+P">P. Fouque</a>, <a href="/search/astro-ph?searchtype=author&query=Alencar%2C+S">S. Alencar</a>, <a href="/search/astro-ph?searchtype=author&query=Artigau%2C+E">E. Artigau</a>, <a href="/search/astro-ph?searchtype=author&query=Boisse%2C+I">I. Boisse</a>, <a href="/search/astro-ph?searchtype=author&query=Bouchy%2C+F">F. Bouchy</a>, <a href="/search/astro-ph?searchtype=author&query=Cadieux%2C+C">C. Cadieux</a>, <a href="/search/astro-ph?searchtype=author&query=Cloutier%2C+R">R. Cloutier</a>, <a href="/search/astro-ph?searchtype=author&query=Cook%2C+N">N. Cook</a>, <a href="/search/astro-ph?searchtype=author&query=Delfosse%2C+X">X. Delfosse</a>, <a href="/search/astro-ph?searchtype=author&query=Doyon%2C+R">R. Doyon</a>, <a href="/search/astro-ph?searchtype=author&query=Hebrard%2C+G">G. Hebrard</a>, <a href="/search/astro-ph?searchtype=author&query=Kochukhov%2C+O">O. Kochukhov</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="2307.01016v1-abstract-short" style="display: inline;"> One manifestation of dynamo action on the Sun is the 22-yr magnetic cycle, exhibiting a polarity reversal and a periodic conversion between poloidal and toroidal fields. For M dwarfs, several authors claim evidence of activity cycles from photometry and analyses of spectroscopic indices, but no clear polarity reversal has been identified from spectropolarimetric observations. Our aim is to monitor… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2307.01016v1-abstract-full').style.display = 'inline'; document.getElementById('2307.01016v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2307.01016v1-abstract-full" style="display: none;"> One manifestation of dynamo action on the Sun is the 22-yr magnetic cycle, exhibiting a polarity reversal and a periodic conversion between poloidal and toroidal fields. For M dwarfs, several authors claim evidence of activity cycles from photometry and analyses of spectroscopic indices, but no clear polarity reversal has been identified from spectropolarimetric observations. Our aim is to monitor the evolution of the large-scale field of AD Leo, which has shown hints of a secular evolution from past dedicated spectropolarimetric campaigns. We analysed near-infrared spectropolarimetric observations of the active M dwarf AD Leo taken with SPIRou between 2019 and 2020 and archival optical data collected with ESPaDOnS and Narval between 2006 and 2019. We searched for long-term variability in the longitudinal field, the width of unpolarised Stokes profiles, the unsigned magnetic flux derived from Zeeman broadening, and the geometry of the large-scale magnetic field using both Zeeman-Doppler Imaging and Principal Component Analysis. We found evidence of a long-term evolution of the magnetic field, featuring a decrease in axisymmetry (from 99% to 60%). This is accompanied by a weakening of the longitudinal field (-300 to -50 G) and a correlated increase in the unsigned magnetic flux (2.8 to 3.6 kG). Likewise, the width of the mean profile computed with selected near-infrared lines manifests a long-term evolution corresponding to field strength changes over the full time series, but does not exhibit modulation with the stellar rotation of AD Leo in individual epochs. The large-scale magnetic field of AD Leo manifested first hints of a polarity reversal in late 2020 in the form of a substantially increased dipole obliquity, while the topology remained predominantly poloidal and dipolar. This suggests that low-mass M dwarfs with a dipole-dominated magnetic field can undergo magnetic cycles. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2307.01016v1-abstract-full').style.display = 'none'; document.getElementById('2307.01016v1-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 July, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> July 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">26 pages, 18 figures, 8 tables</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> A&A 676, A56 (2023) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2306.15877">arXiv:2306.15877</a> <span> [<a href="https://arxiv.org/pdf/2306.15877">pdf</a>, <a href="https://arxiv.org/format/2306.15877">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> </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/10.1038/s41586-023-06029-0">10.1038/s41586-023-06029-0 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> A close-in giant planet escapes engulfment by its star </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Hon%2C+M">Marc Hon</a>, <a href="/search/astro-ph?searchtype=author&query=Huber%2C+D">Daniel Huber</a>, <a href="/search/astro-ph?searchtype=author&query=Rui%2C+N+Z">Nicholas Z. Rui</a>, <a href="/search/astro-ph?searchtype=author&query=Fuller%2C+J">Jim Fuller</a>, <a href="/search/astro-ph?searchtype=author&query=Veras%2C+D">Dimitri Veras</a>, <a href="/search/astro-ph?searchtype=author&query=Kuszlewicz%2C+J+S">James S. Kuszlewicz</a>, <a href="/search/astro-ph?searchtype=author&query=Kochukhov%2C+O">Oleg Kochukhov</a>, <a href="/search/astro-ph?searchtype=author&query=Stokholm%2C+A">Amalie Stokholm</a>, <a href="/search/astro-ph?searchtype=author&query=R%C3%B8rsted%2C+J+L">Jakob Lysgaard R酶rsted</a>, <a href="/search/astro-ph?searchtype=author&query=Y%C4%B1ld%C4%B1z%2C+M">Mutlu Y谋ld谋z</a>, <a href="/search/astro-ph?searchtype=author&query=Orhan%2C+Z+%C3%87">Zeynep 脟elik Orhan</a>, <a href="/search/astro-ph?searchtype=author&query=%C3%96rtel%2C+S">Sibel 脰rtel</a>, <a href="/search/astro-ph?searchtype=author&query=Jiang%2C+C">Chen Jiang</a>, <a href="/search/astro-ph?searchtype=author&query=Hey%2C+D+R">Daniel R. Hey</a>, <a href="/search/astro-ph?searchtype=author&query=Isaacson%2C+H">Howard Isaacson</a>, <a href="/search/astro-ph?searchtype=author&query=Zhang%2C+J">Jingwen Zhang</a>, <a href="/search/astro-ph?searchtype=author&query=Vrard%2C+M">Mathieu Vrard</a>, <a href="/search/astro-ph?searchtype=author&query=Stassun%2C+K+G">Keivan G. Stassun</a>, <a href="/search/astro-ph?searchtype=author&query=Shappee%2C+B+J">Benjamin J. Shappee</a>, <a href="/search/astro-ph?searchtype=author&query=Tayar%2C+J">Jamie Tayar</a>, <a href="/search/astro-ph?searchtype=author&query=Claytor%2C+Z+R">Zachary R. Claytor</a>, <a href="/search/astro-ph?searchtype=author&query=Beard%2C+C">Corey Beard</a>, <a href="/search/astro-ph?searchtype=author&query=Bedding%2C+T+R">Timothy R. Bedding</a>, <a href="/search/astro-ph?searchtype=author&query=Brinkman%2C+C">Casey Brinkman</a>, <a href="/search/astro-ph?searchtype=author&query=Campante%2C+T+L">Tiago L. Campante</a> , et al. (17 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="2306.15877v1-abstract-short" style="display: inline;"> When main-sequence stars expand into red giants, they are expected to engulf close-in planets. Until now, the absence of planets with short orbital periods around post-expansion, core-helium-burning red giants has been interpreted as evidence that short-period planets around Sun-like stars do not survive the giant expansion phase of their host stars. Here we present the discovery that the giant pl… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2306.15877v1-abstract-full').style.display = 'inline'; document.getElementById('2306.15877v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2306.15877v1-abstract-full" style="display: none;"> When main-sequence stars expand into red giants, they are expected to engulf close-in planets. Until now, the absence of planets with short orbital periods around post-expansion, core-helium-burning red giants has been interpreted as evidence that short-period planets around Sun-like stars do not survive the giant expansion phase of their host stars. Here we present the discovery that the giant planet 8 Ursae Minoris b orbits a core-helium-burning red giant. At a distance of only 0.5 au from its host star, the planet would have been engulfed by its host star, which is predicted by standard single-star evolution to have previously expanded to a radius of 0.7 au. Given the brief lifetime of helium-burning giants, the nearly circular orbit of the planet is challenging to reconcile with scenarios in which the planet survives by having a distant orbit initially. Instead, the planet may have avoided engulfment through a stellar merger that either altered the evolution of the host star or produced 8 Ursae Minoris b as a second-generation planet. This system shows that core-helium-burning red giants can harbour close planets and provides evidence for the role of non-canonical stellar evolution in the extended survival of late-stage exoplanetary systems. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2306.15877v1-abstract-full').style.display = 'none'; document.getElementById('2306.15877v1-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 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 Nature on 28 June 2023. In press</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2306.07838">arXiv:2306.07838</a> <span> [<a href="https://arxiv.org/pdf/2306.07838">pdf</a>, <a href="https://arxiv.org/ps/2306.07838">ps</a>, <a href="https://arxiv.org/format/2306.07838">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="Instrumentation and Methods for Astrophysics">astro-ph.IM</span> </div> </div> <p class="title is-5 mathjax"> From convective stellar dynamo simulations to Zeeman-Doppler images </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Hackman%2C+T">Thomas Hackman</a>, <a href="/search/astro-ph?searchtype=author&query=Kochukhov%2C+O">Oleg Kochukhov</a>, <a href="/search/astro-ph?searchtype=author&query=Viviani%2C+M">Mariangela Viviani</a>, <a href="/search/astro-ph?searchtype=author&query=Warnecke%2C+J">J枚rn Warnecke</a>, <a href="/search/astro-ph?searchtype=author&query=Korpi-Lagg%2C+M+J">Maarit J. Korpi-Lagg</a>, <a href="/search/astro-ph?searchtype=author&query=Lehtinen%2C+J+J">Jyri J. Lehtinen</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="2306.07838v2-abstract-short" style="display: inline;"> Zeeman-Doppler imaging (ZDI) is used to reconstruct the surface magnetic field of late-type stars from high resolution spectropolarimetric observations. The results are usually described in terms of characteristics of the field topology, i.e. poloidality vs. toroidality and axi-symmetry vs. non-axisymmetry in addition to the field strength. We want to test how well these characteristics are preser… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2306.07838v2-abstract-full').style.display = 'inline'; document.getElementById('2306.07838v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2306.07838v2-abstract-full" style="display: none;"> Zeeman-Doppler imaging (ZDI) is used to reconstruct the surface magnetic field of late-type stars from high resolution spectropolarimetric observations. The results are usually described in terms of characteristics of the field topology, i.e. poloidality vs. toroidality and axi-symmetry vs. non-axisymmetry in addition to the field strength. We want to test how well these characteristics are preserved when applying the ZDI method on simulated data, i.e. how accurately the field topology is preserved and to what extent stellar parameters influence the reconstruction. We use published magnetic field data from direct numerical MHD simulations. These have variable rotation rates, and hence represent different levels of activity, of an otherwise Sun-like setup. Our ZDI reconstruction is based on spherical harmonics expansion. By comparing the original values to those of the reconstructed images, we study the ability to reconstruct the surface magnetic field in terms of various characteristics of the field. The main large-scale features are reasonably well recovered, but the strength of the recovered magnetic field is just a fraction of the original input. The quality of the reconstruction shows clear correlations with the data quality. Furthermore, there are some spurious dependencies between stellar parameters and the characteristics of the field. Our study uncovers some limits of ZDI. Firstly, the recovered field strength will generally be lower than the "real" value as smaller structures with opposite polarities will be blurred in the inversion. Secondly, the axisymmetry is overestimated. The poloidality vs. toroidality is better recovered. The reconstruction works better for a stronger field and faster rotation velocity. Still, the ZDI method works surprisingly well even for a weaker field and slow rotation, provided the data has a high signal-to-noise and good rotation phase coverage. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2306.07838v2-abstract-full').style.display = 'none'; document.getElementById('2306.07838v2-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, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 13 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">12 pages, 21 figures, A&A, in press, abstract shortened</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2305.06873">arXiv:2305.06873</a> <span> [<a href="https://arxiv.org/pdf/2305.06873">pdf</a>, <a href="https://arxiv.org/format/2305.06873">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> </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/10.1051/0004-6361/202346314">10.1051/0004-6361/202346314 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Determination of small-scale magnetic fields on Sun-like stars in the near-infrared using CRIRES$^+$ </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Hahlin%2C+A">A. Hahlin</a>, <a href="/search/astro-ph?searchtype=author&query=Kochukhov%2C+O">O. Kochukhov</a>, <a href="/search/astro-ph?searchtype=author&query=Rains%2C+A+D">A. D. Rains</a>, <a href="/search/astro-ph?searchtype=author&query=Lavail%2C+A">A. Lavail</a>, <a href="/search/astro-ph?searchtype=author&query=Hatzes%2C+A">A. Hatzes</a>, <a href="/search/astro-ph?searchtype=author&query=Piskunov%2C+N">N. Piskunov</a>, <a href="/search/astro-ph?searchtype=author&query=Reiners%2C+A">A. Reiners</a>, <a href="/search/astro-ph?searchtype=author&query=Seemann%2C+U">U. Seemann</a>, <a href="/search/astro-ph?searchtype=author&query=Boldt-Christmas%2C+L">L. Boldt-Christmas</a>, <a href="/search/astro-ph?searchtype=author&query=Guenther%2C+E+W">E. W. Guenther</a>, <a href="/search/astro-ph?searchtype=author&query=Heiter%2C+U">U. Heiter</a>, <a href="/search/astro-ph?searchtype=author&query=Nortmann%2C+L">L. Nortmann</a>, <a href="/search/astro-ph?searchtype=author&query=Yan%2C+F">F. Yan</a>, <a href="/search/astro-ph?searchtype=author&query=Shulyak%2C+D">D. Shulyak</a>, <a href="/search/astro-ph?searchtype=author&query=Smoker%2C+J+V">J. V. Smoker</a>, <a href="/search/astro-ph?searchtype=author&query=Rodler%2C+F">F. Rodler</a>, <a href="/search/astro-ph?searchtype=author&query=Bristow%2C+P">P. Bristow</a>, <a href="/search/astro-ph?searchtype=author&query=Dorn%2C+R+J">R. J. Dorn</a>, <a href="/search/astro-ph?searchtype=author&query=Jung%2C+Y">Y. Jung</a>, <a href="/search/astro-ph?searchtype=author&query=Marquart%2C+T">T. Marquart</a>, <a href="/search/astro-ph?searchtype=author&query=Stempels%2C+E">E. Stempels</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="2305.06873v1-abstract-short" style="display: inline;"> We aim to characterise the small-scale magnetic fields for a sample of 16 Sun-like stars and investigate the capabilities of the newly upgraded near-infrared (NIR) instrument CRIRES$^+$ at the VLT in the context of small-scale magnetic field studies. Our targets also had their magnetic fields studied in the optical, which allows us to compare magnetic field properties at different spatial scales o… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2305.06873v1-abstract-full').style.display = 'inline'; document.getElementById('2305.06873v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2305.06873v1-abstract-full" style="display: none;"> We aim to characterise the small-scale magnetic fields for a sample of 16 Sun-like stars and investigate the capabilities of the newly upgraded near-infrared (NIR) instrument CRIRES$^+$ at the VLT in the context of small-scale magnetic field studies. Our targets also had their magnetic fields studied in the optical, which allows us to compare magnetic field properties at different spatial scales on the stellar surface and to contrast small-scale magnetic field measurements at different wavelengths. We analyse the Zeeman broadening signature for six magnetically sensitive and insensitive \ion{Fe}{I} lines in the H-band to measure small-scale magnetic fields on the stellar surface. We use polarised radiative transfer modelling and NLTE departure coefficients in combination with MCMC to determine magnetic field characteristics together with non-magnetic stellar parameters. We use two different approaches to describe small-scale magnetic fields. The first is a two-component model with a single magnetic region and a free magnetic field strength. The second model contains multiple magnetic components with fixed magnetic field strengths. We find average magnetic field strengths ranging from $\sim 0.4$ kG down to $<0.1$ kG. The results align closely with other results from high resolution NIR spectrographs such as SPIRou. We find that the small-scale fields correlate with the large-scale fields and that the small-scale fields are at least 10 times stronger than the large-scale fields inferred with Zeeman Doppler imaging. The two- and multi-component models produce systematically different results as the strong fields from the multi-component model increase the obtained mean magnetic field strength. When comparing our results with the optical measurements of small-scale fields we find a systematic offset of 2--3 times stronger fields in the optical. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2305.06873v1-abstract-full').style.display = 'none'; document.getElementById('2305.06873v1-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 May, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> May 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">28 pages, 23 figures, accepted by A&A</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> A&A 675, A91 (2023) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2304.09896">arXiv:2304.09896</a> <span> [<a href="https://arxiv.org/pdf/2304.09896">pdf</a>, <a href="https://arxiv.org/format/2304.09896">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> </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/acce38">10.3847/2041-8213/acce38 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Constraints on Magnetic Braking from the G8 Dwarf Stars 61 UMa and $蟿$ Cet </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Metcalfe%2C+T+S">Travis S. Metcalfe</a>, <a href="/search/astro-ph?searchtype=author&query=Strassmeier%2C+K+G">Klaus G. Strassmeier</a>, <a href="/search/astro-ph?searchtype=author&query=Ilyin%2C+I+V">Ilya V. Ilyin</a>, <a href="/search/astro-ph?searchtype=author&query=van+Saders%2C+J+L">Jennifer L. van Saders</a>, <a href="/search/astro-ph?searchtype=author&query=Ayres%2C+T+R">Thomas R. Ayres</a>, <a href="/search/astro-ph?searchtype=author&query=Finley%2C+A+J">Adam J. Finley</a>, <a href="/search/astro-ph?searchtype=author&query=Kochukhov%2C+O">Oleg Kochukhov</a>, <a href="/search/astro-ph?searchtype=author&query=Petit%2C+P">Pascal Petit</a>, <a href="/search/astro-ph?searchtype=author&query=See%2C+V">Victor See</a>, <a href="/search/astro-ph?searchtype=author&query=Stassun%2C+K+G">Keivan G. Stassun</a>, <a href="/search/astro-ph?searchtype=author&query=Jeffers%2C+S+V">Sandra V. Jeffers</a>, <a href="/search/astro-ph?searchtype=author&query=Marsden%2C+S+C">Stephen C. Marsden</a>, <a href="/search/astro-ph?searchtype=author&query=Morin%2C+J">Julien Morin</a>, <a href="/search/astro-ph?searchtype=author&query=Vidotto%2C+A+A">Aline A. Vidotto</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="2304.09896v1-abstract-short" style="display: inline;"> During the first half of their main-sequence lifetimes, stars rapidly lose angular momentum to their magnetized winds, a process known as magnetic braking. Recent observations suggest a substantial decrease in the magnetic braking efficiency when stars reach a critical value of the Rossby number, the stellar rotation period normalized by the convective overturn timescale. Cooler stars have deeper… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2304.09896v1-abstract-full').style.display = 'inline'; document.getElementById('2304.09896v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2304.09896v1-abstract-full" style="display: none;"> During the first half of their main-sequence lifetimes, stars rapidly lose angular momentum to their magnetized winds, a process known as magnetic braking. Recent observations suggest a substantial decrease in the magnetic braking efficiency when stars reach a critical value of the Rossby number, the stellar rotation period normalized by the convective overturn timescale. Cooler stars have deeper convection zones with longer overturn times, reaching this critical Rossby number at slower rotation rates. The nature and timing of the transition to weakened magnetic braking has previously been constrained by several solar analogs and two slightly hotter stars. In this Letter, we derive the first direct constraints from stars cooler than the Sun. We present new spectropolarimetry of the old G8 dwarf $蟿$ Cet from the Large Binocular Telescope, and we reanalyze a published Zeeman Doppler image of the younger G8 star 61 UMa, yielding the large-scale magnetic field strengths and morphologies. We estimate mass-loss rates using archival X-ray observations and inferences from Ly$伪$ measurements, and we adopt other stellar properties from asteroseismology and spectral energy distribution fitting. The resulting calculations of the wind braking torque demonstrate that the rate of angular momentum loss drops by a factor of 300 between the ages of these two stars (1.4-9 Gyr), well above theoretical expectations. We summarize the available data to help constrain the value of the critical Rossby number, and we identify a new signature of the long-period detection edge in recent measurements from the Kepler mission. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2304.09896v1-abstract-full').style.display = 'none'; document.getElementById('2304.09896v1-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 April, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> April 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">ApJ Letters (accepted), 6 pages including 3 figures and 1 table. Python code is available at https://github.com/travismetcalfe/FinleyMatt2018</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Astrophys. J. 948, L6 (2023) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2303.03862">arXiv:2303.03862</a> <span> [<a href="https://arxiv.org/pdf/2303.03862">pdf</a>, <a href="https://arxiv.org/format/2303.03862">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> </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/stad720">10.1093/mnras/stad720 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Surface structure of 45 Hercules: An otherwise unremarkable Ap star with a surprisingly weak magnetic field </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Kochukhov%2C+O">O. Kochukhov</a>, <a href="/search/astro-ph?searchtype=author&query=Mutlay%2C+H+G">H. G眉rsoytrak Mutlay</a>, <a href="/search/astro-ph?searchtype=author&query=Amarsi%2C+A+M">A. M. Amarsi</a>, <a href="/search/astro-ph?searchtype=author&query=Petit%2C+P">P. Petit</a>, <a href="/search/astro-ph?searchtype=author&query=Mutlay%2C+I">I. Mutlay</a>, <a href="/search/astro-ph?searchtype=author&query=G%C3%BCrol%2C+B">B. G眉rol</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="2303.03862v1-abstract-short" style="display: inline;"> The origin of magnetic fields and their role in chemical spot formation on magnetic Ap stars is currently not understood. Here we contribute to solving this problem with a detailed observational characterisation of the surface structure of 45 Her, a weak-field Ap star. We find this object to be a long-period, single-lined spectroscopic binary and determine the binary orbit as well as fundamental a… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2303.03862v1-abstract-full').style.display = 'inline'; document.getElementById('2303.03862v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2303.03862v1-abstract-full" style="display: none;"> The origin of magnetic fields and their role in chemical spot formation on magnetic Ap stars is currently not understood. Here we contribute to solving this problem with a detailed observational characterisation of the surface structure of 45 Her, a weak-field Ap star. We find this object to be a long-period, single-lined spectroscopic binary and determine the binary orbit as well as fundamental and atmospheric parameters of the primary. We study magnetic field topology and chemical spot distribution of 45 Her with the help of the Zeeman Doppler imaging technique. Magnetic mapping reveals the stellar surface field to have a distorted dipolar topology with a surface-averaged field strength of 77 G and a dipolar component strength of 119 G - confirming it as one of the weakest well-characterised Ap-star fields known. Despite its feeble magnetic field, 45 Her shows surface chemical inhomogeneities with abundance contrasts of up to 6 dex. Of the four chemical elements studied, O concentrates at the magnetic equator whereas Ti, Cr and Fe avoid this region. Apart from this trend, the positions of Fe-peak element spots show no apparent correlation with the magnetic field geometry. No signs of surface differential rotation or temporal evolution of chemical spots on the time scale of several years were detected. Our findings demonstrate that chemical spot formation does not require strong magnetic fields to proceed and that both the stellar structure and the global field itself remain stable for sub-100 G field strengths contrary to theoretical predictions. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2303.03862v1-abstract-full').style.display = 'none'; document.getElementById('2303.03862v1-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> 7 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">15 pages, 19 figures; Accepted for publication in MNRAS</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2302.08736">arXiv:2302.08736</a> <span> [<a href="https://arxiv.org/pdf/2302.08736">pdf</a>, <a href="https://arxiv.org/format/2302.08736">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Earth and Planetary Astrophysics">astro-ph.EP</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/10.1051/0004-6361/202245371">10.1051/0004-6361/202245371 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> CRIRES+ detection of CO emissions lines and temperature inversions on the dayside of WASP-18b and WASP-76b </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Yan%2C+F">F. Yan</a>, <a href="/search/astro-ph?searchtype=author&query=Nortmann%2C+L">L. Nortmann</a>, <a href="/search/astro-ph?searchtype=author&query=Reiners%2C+A">A. Reiners</a>, <a href="/search/astro-ph?searchtype=author&query=Piskunov%2C+N">N. Piskunov</a>, <a href="/search/astro-ph?searchtype=author&query=Hatzes%2C+A">A. Hatzes</a>, <a href="/search/astro-ph?searchtype=author&query=Seemann%2C+U">U. Seemann</a>, <a href="/search/astro-ph?searchtype=author&query=Shulyak%2C+D">D. Shulyak</a>, <a href="/search/astro-ph?searchtype=author&query=Lavail%2C+A">A. Lavail</a>, <a href="/search/astro-ph?searchtype=author&query=Rains%2C+A+D">A. D. Rains</a>, <a href="/search/astro-ph?searchtype=author&query=Cont%2C+D">D. Cont</a>, <a href="/search/astro-ph?searchtype=author&query=Rengel%2C+M">M. Rengel</a>, <a href="/search/astro-ph?searchtype=author&query=Lesjak%2C+F">F. Lesjak</a>, <a href="/search/astro-ph?searchtype=author&query=Nagel%2C+E">E. Nagel</a>, <a href="/search/astro-ph?searchtype=author&query=Kochukhov%2C+O">O. Kochukhov</a>, <a href="/search/astro-ph?searchtype=author&query=Czesla%2C+S">S. Czesla</a>, <a href="/search/astro-ph?searchtype=author&query=Boldt-Christmas%2C+L">L. Boldt-Christmas</a>, <a href="/search/astro-ph?searchtype=author&query=Heiter%2C+U">U. Heiter</a>, <a href="/search/astro-ph?searchtype=author&query=Smoker%2C+J+V">J. V. Smoker</a>, <a href="/search/astro-ph?searchtype=author&query=Rodler%2C+F">F. Rodler</a>, <a href="/search/astro-ph?searchtype=author&query=Bristow%2C+P">P. Bristow</a>, <a href="/search/astro-ph?searchtype=author&query=Dorn%2C+R+J">R. J. Dorn</a>, <a href="/search/astro-ph?searchtype=author&query=Jung%2C+Y">Y. Jung</a>, <a href="/search/astro-ph?searchtype=author&query=Marquart%2C+T">T. Marquart</a>, <a href="/search/astro-ph?searchtype=author&query=Stempels%2C+E">E. Stempels</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="2302.08736v1-abstract-short" style="display: inline;"> The dayside atmospheres of ultra-hot Jupiters (UHJs) are predicted to possess temperature inversion layers with extremely high temperatures at high altitudes. We observed the dayside thermal emission spectra of WASP-18b and WASP-76b with the new CRIRES+ high-resolution spectrograph at near-infrared wavelengths. Using the cross-correlation technique, we detected strong CO emission lines in both pla… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2302.08736v1-abstract-full').style.display = 'inline'; document.getElementById('2302.08736v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2302.08736v1-abstract-full" style="display: none;"> The dayside atmospheres of ultra-hot Jupiters (UHJs) are predicted to possess temperature inversion layers with extremely high temperatures at high altitudes. We observed the dayside thermal emission spectra of WASP-18b and WASP-76b with the new CRIRES+ high-resolution spectrograph at near-infrared wavelengths. Using the cross-correlation technique, we detected strong CO emission lines in both planets, which confirms the existence of temperature inversions on their dayside hemispheres. The two planets are the first UHJs orbiting F-type stars with CO emission lines detected; previous detections were mostly for UHJs orbiting A-type stars. Evidence of weak H2O emission signals is also found for both planets. We further applied forward-model retrievals on the detected CO lines and retrieved the temperature-pressure profiles along with the CO volume mixing ratios. The retrieved logarithmic CO mixing ratio of WASP-18b (-2.2) is slightly higher than the value predicted by the self-consistent model assuming solar abundance. For WASP-76b, the retrieved CO mixing ratio (-3.6) is broadly consistent with the value of solar abundance. In addition, we included the equatorial rotation velocity (Veq ) in the retrieval when analyzing the line profile broadening. The obtained Veq is 7.0 km/s for WASP-18b and 5.2 km/s for WASP-76b, which are consistent with the tidally locked rotational velocities. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2302.08736v1-abstract-full').style.display = 'none'; document.getElementById('2302.08736v1-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 February, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> February 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, 12 figures; accepted for publication in A&A</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> A&A 672, A107 (2023) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2301.08048">arXiv:2301.08048</a> <span> [<a href="https://arxiv.org/pdf/2301.08048">pdf</a>, <a href="https://arxiv.org/format/2301.08048">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> </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/10.1051/0004-6361/202245217">10.1051/0004-6361/202245217 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> CRIRES$^{+}$ on sky at the ESO Very Large Telescope </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Dorn%2C+R+J">R. J. Dorn</a>, <a href="/search/astro-ph?searchtype=author&query=Bristow%2C+P">P. Bristow</a>, <a href="/search/astro-ph?searchtype=author&query=Smoker%2C+J+V">J. V. Smoker</a>, <a href="/search/astro-ph?searchtype=author&query=Rodler%2C+F">F. Rodler</a>, <a href="/search/astro-ph?searchtype=author&query=Lavail%2C+A">A. Lavail</a>, <a href="/search/astro-ph?searchtype=author&query=Accardo%2C+M">M. Accardo</a>, <a href="/search/astro-ph?searchtype=author&query=Ancker%2C+M+v+d">M. van den Ancker</a>, <a href="/search/astro-ph?searchtype=author&query=Baade%2C+D">D. Baade</a>, <a href="/search/astro-ph?searchtype=author&query=Baruffolo%2C+A">A. Baruffolo</a>, <a href="/search/astro-ph?searchtype=author&query=Courtney-Barrer%2C+B">B. Courtney-Barrer</a>, <a href="/search/astro-ph?searchtype=author&query=Blanco%2C+L">L. Blanco</a>, <a href="/search/astro-ph?searchtype=author&query=Brucalassi%2C+A">A. Brucalassi</a>, <a href="/search/astro-ph?searchtype=author&query=Cumani%2C+C">C. Cumani</a>, <a href="/search/astro-ph?searchtype=author&query=Follert%2C+R">R. Follert</a>, <a href="/search/astro-ph?searchtype=author&query=Haimerl%2C+A">A. Haimerl</a>, <a href="/search/astro-ph?searchtype=author&query=Hatzes%2C+A">A. Hatzes</a>, <a href="/search/astro-ph?searchtype=author&query=Haug%2C+M">M. Haug</a>, <a href="/search/astro-ph?searchtype=author&query=Heiter%2C+U">U. Heiter</a>, <a href="/search/astro-ph?searchtype=author&query=Hinterschuster%2C+R">R. Hinterschuster</a>, <a href="/search/astro-ph?searchtype=author&query=Hubin%2C+N">N. Hubin</a>, <a href="/search/astro-ph?searchtype=author&query=Ives%2C+D+J">D. J. Ives</a>, <a href="/search/astro-ph?searchtype=author&query=Jung%2C+Y">Y. Jung</a>, <a href="/search/astro-ph?searchtype=author&query=Jones%2C+M">M. Jones</a>, <a href="/search/astro-ph?searchtype=author&query=Kirchbauer%2C+J">J-P. Kirchbauer</a>, <a href="/search/astro-ph?searchtype=author&query=Klein%2C+B">B. Klein</a> , et al. (27 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="2301.08048v1-abstract-short" style="display: inline;"> The CRyogenic InfraRed Echelle Spectrograph (CRIRES) Upgrade project CRIRES$^{+}$ extended the capabilities of CRIRES. It transformed this VLT instrument into a cross-dispersed spectrograph to increase the wavelength range that is covered simultaneously by up to a factor of ten. In addition, a new detector focal plane array of three Hawaii 2RG detectors with a 5.3 $渭$m cutoff wavelength replaced t… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2301.08048v1-abstract-full').style.display = 'inline'; document.getElementById('2301.08048v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2301.08048v1-abstract-full" style="display: none;"> The CRyogenic InfraRed Echelle Spectrograph (CRIRES) Upgrade project CRIRES$^{+}$ extended the capabilities of CRIRES. It transformed this VLT instrument into a cross-dispersed spectrograph to increase the wavelength range that is covered simultaneously by up to a factor of ten. In addition, a new detector focal plane array of three Hawaii 2RG detectors with a 5.3 $渭$m cutoff wavelength replaced the existing detectors. Amongst many other improvements, a new spectropolarimetric unit was added and the calibration system has been enhanced. The instrument was installed at the VLT on Unit Telescope 3 at the beginning of 2020 and successfully commissioned and verified for science operations during 2021, partly remotely from Europe due to the COVID-19 pandemic. The instrument was subsequently offered to the community from October 2021 onwards. This article describes the performance and capabilities of the upgraded instrument and presents on sky results. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2301.08048v1-abstract-full').style.display = 'none'; document.getElementById('2301.08048v1-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 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 for publication in Astronomy and Astrophysics</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> A&A 671, A24 (2023) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2211.06191">arXiv:2211.06191</a> <span> [<a href="https://arxiv.org/pdf/2211.06191">pdf</a>, <a href="https://arxiv.org/format/2211.06191">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="High Energy Astrophysical Phenomena">astro-ph.HE</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/stac3322">10.1093/mnras/stac3322 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Accretion process, magnetic fields, and apsidal motion in the pre-main sequence binary DQ Tau </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Pouilly%2C+K">Kim Pouilly</a>, <a href="/search/astro-ph?searchtype=author&query=Kochukhov%2C+O">Oleg Kochukhov</a>, <a href="/search/astro-ph?searchtype=author&query=K%C3%B3sp%C3%A1l%2C+%C3%81">脕gnes K贸sp谩l</a>, <a href="/search/astro-ph?searchtype=author&query=Hahlin%2C+A">Axel Hahlin</a>, <a href="/search/astro-ph?searchtype=author&query=Carmona%2C+A">Andres Carmona</a>, <a href="/search/astro-ph?searchtype=author&query=%C3%81brah%C3%A1m%2C+P">P茅ter 脕brah谩m</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="2211.06191v1-abstract-short" style="display: inline;"> Classical T Tauri stars (CTTSs) are young stellar objects that accrete materials from their accretion disc influenced by their strong magnetic field. The magnetic pressure truncates the disc at a few stellar radii and forces the material to leave the disc plane and fall onto the stellar surface by following the magnetic field lines. However, this global scheme may be disturbed by the presence of a… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2211.06191v1-abstract-full').style.display = 'inline'; document.getElementById('2211.06191v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2211.06191v1-abstract-full" style="display: none;"> Classical T Tauri stars (CTTSs) are young stellar objects that accrete materials from their accretion disc influenced by their strong magnetic field. The magnetic pressure truncates the disc at a few stellar radii and forces the material to leave the disc plane and fall onto the stellar surface by following the magnetic field lines. However, this global scheme may be disturbed by the presence of a companion interacting gravitationally with the accreting component. This work is aiming to study the accretion and the magnetic field of the tight eccentric binary DQ Tau, composed of two equal-mass ($\sim$ 0.6 \msun ) CTTSs interacting at different orbital phases. We investigated the variability of the system using a high-resolution spectroscopic and spectropolarimetric monitoring performed with ESPaDOnS at the CFHT. We provide the first ever magnetic field analysis of this system, the Zeeman-Doppler imaging revealed a stronger magnetic field for the secondary than the primary (1.2 kG and 0.5 kG, respectively), but the small-scale fields analysed through Zeeman intensification yielded similar strengths (about 2.5 kG). The magnetic field topology and strengths are compatible with the accretion processes on CTTSs. Both components of this system are accreting, with a change of the main accretor during the orbital motion. In addition, the system displays a strong enhancement of the mass accretion rate at periastron and apastron. We also discovered, for the first time in this system, the apsidal motion of the orbital ellipse. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2211.06191v1-abstract-full').style.display = 'none'; document.getElementById('2211.06191v1-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 November, 2022; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> November 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">18 pages, 20 figures. Accepted for publication in MNRAS</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2207.12970">arXiv:2207.12970</a> <span> [<a href="https://arxiv.org/pdf/2207.12970">pdf</a>, <a href="https://arxiv.org/format/2207.12970">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="Instrumentation and Methods for Astrophysics">astro-ph.IM</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/10.1007/s10509-022-04113-x">10.1007/s10509-022-04113-x <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Ultraviolet Spectropolarimetry With Polstar: Using Polstar to test Magnetospheric Mass-loss Quenching </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Shultz%2C+M+E">M. E. Shultz</a>, <a href="/search/astro-ph?searchtype=author&query=Casini%2C+R">R. Casini</a>, <a href="/search/astro-ph?searchtype=author&query=Cheung%2C+M+C+M">M. C. M. Cheung</a>, <a href="/search/astro-ph?searchtype=author&query=David-Uraz%2C+A">A. David-Uraz</a>, <a href="/search/astro-ph?searchtype=author&query=Alem%C3%A1n%2C+T+d+P">T. del Pino Alem谩n</a>, <a href="/search/astro-ph?searchtype=author&query=Erba%2C+C">C. Erba</a>, <a href="/search/astro-ph?searchtype=author&query=Folsom%2C+C+P">C. P. Folsom</a>, <a href="/search/astro-ph?searchtype=author&query=Gayley%2C+K">K. Gayley</a>, <a href="/search/astro-ph?searchtype=author&query=Ignace%2C+R">R. Ignace</a>, <a href="/search/astro-ph?searchtype=author&query=Keszthelyi%2C+Z">Z. Keszthelyi</a>, <a href="/search/astro-ph?searchtype=author&query=Kochukhov%2C+O">O. Kochukhov</a>, <a href="/search/astro-ph?searchtype=author&query=Naz%C3%A9%2C+Y">Y. Naz茅</a>, <a href="/search/astro-ph?searchtype=author&query=Neiner%2C+C">C. Neiner</a>, <a href="/search/astro-ph?searchtype=author&query=Oksala%2C+M">M. Oksala</a>, <a href="/search/astro-ph?searchtype=author&query=Petit%2C+V">V. Petit</a>, <a href="/search/astro-ph?searchtype=author&query=Scowen%2C+P+A">P. A. Scowen</a>, <a href="/search/astro-ph?searchtype=author&query=Sudnik%2C+N">N. Sudnik</a>, <a href="/search/astro-ph?searchtype=author&query=ud-Doula%2C+A">A. ud-Doula</a>, <a href="/search/astro-ph?searchtype=author&query=Vink%2C+J+S">J. S. Vink</a>, <a href="/search/astro-ph?searchtype=author&query=Wade%2C+G+A">G. A. Wade</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="2207.12970v1-abstract-short" style="display: inline;"> Polstar is a proposed NASA MIDEX space telescope that will provide high-resolution, simultaneous full-Stokes spectropolarimetry in the far ultraviolet, together with low-resolution linear polarimetry in the near ultraviolet. This observatory offers unprecedented capabilities to obtain unique information on the magnetic and plasma properties of the magnetospheres of hot stars. We describe an observ… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2207.12970v1-abstract-full').style.display = 'inline'; document.getElementById('2207.12970v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2207.12970v1-abstract-full" style="display: none;"> Polstar is a proposed NASA MIDEX space telescope that will provide high-resolution, simultaneous full-Stokes spectropolarimetry in the far ultraviolet, together with low-resolution linear polarimetry in the near ultraviolet. This observatory offers unprecedented capabilities to obtain unique information on the magnetic and plasma properties of the magnetospheres of hot stars. We describe an observing program making use of the known population of magnetic hot stars to test the fundamental hypothesis that magnetospheres should act to rapidly drain angular momentum, thereby spinning the star down, whilst simultaneously reducing the net mass-loss rate. Both effects are expected to lead to dramatic differences in the evolution of magnetic vs. non-magnetic stars. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2207.12970v1-abstract-full').style.display = 'none'; document.getElementById('2207.12970v1-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> 26 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">20 pages, 10 figures, accepted for publication in ApSS. arXiv admin note: substantial text overlap with arXiv:2111.06434</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2207.09255">arXiv:2207.09255</a> <span> [<a href="https://arxiv.org/pdf/2207.09255">pdf</a>, <a href="https://arxiv.org/ps/2207.09255">ps</a>, <a href="https://arxiv.org/format/2207.09255">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> </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/10.1017/S1743921322002174">10.1017/S1743921322002174 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> First results of a magnetic survey of classical Cepheids </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Barron%2C+J+A">James A. Barron</a>, <a href="/search/astro-ph?searchtype=author&query=Wade%2C+G+A">Gregg A. Wade</a>, <a href="/search/astro-ph?searchtype=author&query=Folsom%2C+C+P">Colin P. Folsom</a>, <a href="/search/astro-ph?searchtype=author&query=Kochukhov%2C+O">Oleg Kochukhov</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="2207.09255v1-abstract-short" style="display: inline;"> We report recent ESPaDOnS and HARPSpol spectropolarimetric observations from our ongoing magnetic survey of the brightest twenty-five classical Cepheids. Stokes $V$ magnetic signatures are detected in eight of fifteen targets observed to date. The Stokes $V$ profiles show a diversity of morphologies with weak associated longitudinal field measurements of order 1 G. Many of the Stokes $V$ profiles… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2207.09255v1-abstract-full').style.display = 'inline'; document.getElementById('2207.09255v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2207.09255v1-abstract-full" style="display: none;"> We report recent ESPaDOnS and HARPSpol spectropolarimetric observations from our ongoing magnetic survey of the brightest twenty-five classical Cepheids. Stokes $V$ magnetic signatures are detected in eight of fifteen targets observed to date. The Stokes $V$ profiles show a diversity of morphologies with weak associated longitudinal field measurements of order 1 G. Many of the Stokes $V$ profiles are difficult to interpret in the context of the normal Zeeman effect. They consist of approximately unipolar single or double lobe(s) of positive or negative circular polarization. We hypothesize that these unusual signatures are due to the Zeeman effect modified by atmospheric velocity or magnetic field gradients. In contrast, the Stokes $V$ profiles of Polaris and MY Pup appear qualitatively similar to the complex magnetic signatures of non-pulsating cool supergiants, possibly due to the low pulsation amplitudes of these two stars. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2207.09255v1-abstract-full').style.display = 'none'; document.getElementById('2207.09255v1-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 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">2 pages, 1 figure, to appear in Proceedings of the IAU, Symposium No. 361: Massive Stars Near and Far, 2022, N. St-Louis, J. S. Vink and J. Mackey, eds</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Proc. IAU 18 (2022) 233-235 </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2206.08540">arXiv:2206.08540</a> <span> [<a href="https://arxiv.org/pdf/2206.08540">pdf</a>, <a href="https://arxiv.org/format/2206.08540">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> </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/ac794d">10.3847/2041-8213/ac794d <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> The Origin of Weakened Magnetic Braking in Old Solar Analogs </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Metcalfe%2C+T+S">Travis S. Metcalfe</a>, <a href="/search/astro-ph?searchtype=author&query=Finley%2C+A+J">Adam J. Finley</a>, <a href="/search/astro-ph?searchtype=author&query=Kochukhov%2C+O">Oleg Kochukhov</a>, <a href="/search/astro-ph?searchtype=author&query=See%2C+V">Victor See</a>, <a href="/search/astro-ph?searchtype=author&query=Ayres%2C+T+R">Thomas R. Ayres</a>, <a href="/search/astro-ph?searchtype=author&query=Stassun%2C+K+G">Keivan G. Stassun</a>, <a href="/search/astro-ph?searchtype=author&query=van+Saders%2C+J+L">Jennifer L. van Saders</a>, <a href="/search/astro-ph?searchtype=author&query=Clark%2C+C+A">Catherine A. Clark</a>, <a href="/search/astro-ph?searchtype=author&query=Godoy-Rivera%2C+D">Diego Godoy-Rivera</a>, <a href="/search/astro-ph?searchtype=author&query=Ilyin%2C+I+V">Ilya V. Ilyin</a>, <a href="/search/astro-ph?searchtype=author&query=Pinsonneault%2C+M+H">Marc H. Pinsonneault</a>, <a href="/search/astro-ph?searchtype=author&query=Strassmeier%2C+K+G">Klaus G. Strassmeier</a>, <a href="/search/astro-ph?searchtype=author&query=Petit%2C+P">Pascal Petit</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="2206.08540v1-abstract-short" style="display: inline;"> The rotation rates of main-sequence stars slow over time as they gradually lose angular momentum to their magnetized stellar winds. The rate of angular momentum loss depends on the strength and morphology of the magnetic field, the mass-loss rate, and the stellar rotation period, mass, and radius. Previous observations suggested a shift in magnetic morphology between two F-type stars with similar… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2206.08540v1-abstract-full').style.display = 'inline'; document.getElementById('2206.08540v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2206.08540v1-abstract-full" style="display: none;"> The rotation rates of main-sequence stars slow over time as they gradually lose angular momentum to their magnetized stellar winds. The rate of angular momentum loss depends on the strength and morphology of the magnetic field, the mass-loss rate, and the stellar rotation period, mass, and radius. Previous observations suggested a shift in magnetic morphology between two F-type stars with similar rotation rates but very different ages (88 Leo and rho CrB). In this Letter, we identify a comparable transition in an evolutionary sequence of solar analogs with ages between 2-7 Gyr. We present new spectropolarimetry of 18 Sco and 16 Cyg A & B from the Large Binocular Telescope, and we reanalyze previously published Zeeman Doppler images of HD 76151 and 18 Sco, providing additional constraints on the nature and timing of this transition. We combine archival X-ray observations with updated distances from Gaia to estimate mass-loss rates, and we adopt precise stellar properties from asteroseismology and other sources. We then calculate the wind braking torque for each star in the evolutionary sequence, demonstrating that the rate of angular momentum loss drops by more than an order of magnitude between the ages of HD 76151 and 18 Sco (2.6-3.7 Gyr) and continues to decrease modestly to the age of 16 Cyg A & B (7 Gyr). We suggest that this magnetic transition may represent a disruption of the global dynamo arising from weaker differential rotation, and we outline plans to probe this phenomenon in additional stars spanning a wide range of spectral types. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2206.08540v1-abstract-full').style.display = 'none'; document.getElementById('2206.08540v1-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 June, 2022; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> June 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">6 pages including 2 figures and 1 table. ApJ Letters (accepted June 16)</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Astrophys. J. 933, L17 (2022) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2206.05864">arXiv:2206.05864</a> <span> [<a href="https://arxiv.org/pdf/2206.05864">pdf</a>, <a href="https://arxiv.org/format/2206.05864">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Astrophysics of Galaxies">astro-ph.GA</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="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/10.1051/0004-6361/202243688">10.1051/0004-6361/202243688 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Gaia Data Release 3: Astrophysical parameters inference system (Apsis) I -- methods and content overview </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Creevey%2C+O+L">O. L. Creevey</a>, <a href="/search/astro-ph?searchtype=author&query=Sordo%2C+R">R. Sordo</a>, <a href="/search/astro-ph?searchtype=author&query=Pailler%2C+F">F. Pailler</a>, <a href="/search/astro-ph?searchtype=author&query=Fr%C3%A9mat%2C+Y">Y. Fr茅mat</a>, <a href="/search/astro-ph?searchtype=author&query=Heiter%2C+U">U. Heiter</a>, <a href="/search/astro-ph?searchtype=author&query=Th%C3%A9venin%2C+F">F. Th茅venin</a>, <a href="/search/astro-ph?searchtype=author&query=Andrae%2C+R">R. Andrae</a>, <a href="/search/astro-ph?searchtype=author&query=Fouesneau%2C+M">M. Fouesneau</a>, <a href="/search/astro-ph?searchtype=author&query=Lobel%2C+A">A. Lobel</a>, <a href="/search/astro-ph?searchtype=author&query=Bailer-Jones%2C+C+A+L">C. A. L. Bailer-Jones</a>, <a href="/search/astro-ph?searchtype=author&query=Garabato%2C+D">D. Garabato</a>, <a href="/search/astro-ph?searchtype=author&query=Bellas-Velidis%2C+I">I. Bellas-Velidis</a>, <a href="/search/astro-ph?searchtype=author&query=Brugaletta%2C+E">E. Brugaletta</a>, <a href="/search/astro-ph?searchtype=author&query=Lorca%2C+A">A. Lorca</a>, <a href="/search/astro-ph?searchtype=author&query=Ordenovic%2C+C">C. Ordenovic</a>, <a href="/search/astro-ph?searchtype=author&query=Palicio%2C+P+A">P. A. Palicio</a>, <a href="/search/astro-ph?searchtype=author&query=Sarro%2C+L+M">L. M. Sarro</a>, <a href="/search/astro-ph?searchtype=author&query=Delchambre%2C+L">L. Delchambre</a>, <a href="/search/astro-ph?searchtype=author&query=Drimmel%2C+R">R. Drimmel</a>, <a href="/search/astro-ph?searchtype=author&query=Rybizki%2C+J">J. Rybizki</a>, <a href="/search/astro-ph?searchtype=author&query=Elipe%2C+G+T">G. Torralba Elipe</a>, <a href="/search/astro-ph?searchtype=author&query=Korn%2C+A+J">A. J. Korn</a>, <a href="/search/astro-ph?searchtype=author&query=Recio-Blanco%2C+A">A. Recio-Blanco</a>, <a href="/search/astro-ph?searchtype=author&query=Schultheis%2C+M+S">M. S. Schultheis</a>, <a href="/search/astro-ph?searchtype=author&query=De+Angeli%2C+F">F. De Angeli</a> , et al. (64 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="2206.05864v1-abstract-short" style="display: inline;"> Gaia Data Release 3 contains a wealth of new data products for the community. Astrophysical parameters are a major component of this release. They were produced by the Astrophysical parameters inference system (Apsis) within the Gaia Data Processing and Analysis Consortium. The aim of this paper is to describe the overall content of the astrophysical parameters in Gaia Data Release 3 and how they… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2206.05864v1-abstract-full').style.display = 'inline'; document.getElementById('2206.05864v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2206.05864v1-abstract-full" style="display: none;"> Gaia Data Release 3 contains a wealth of new data products for the community. Astrophysical parameters are a major component of this release. They were produced by the Astrophysical parameters inference system (Apsis) within the Gaia Data Processing and Analysis Consortium. The aim of this paper is to describe the overall content of the astrophysical parameters in Gaia Data Release 3 and how they were produced. In Apsis we use the mean BP/RP and mean RVS spectra along with astrometry and photometry, and we derive the following parameters: source classification and probabilities for 1.6 billion objects, interstellar medium characterisation and distances for up to 470 million sources, including a 2D total Galactic extinction map, 6 million redshifts of quasar candidates and 1.4 million redshifts of galaxy candidates, along with an analysis of 50 million outlier sources through an unsupervised classification. The astrophysical parameters also include many stellar spectroscopic and evolutionary parameters for up to 470 million sources. These comprise Teff, logg, and m_h (470 million using BP/RP, 6 million using RVS), radius (470 million), mass (140 million), age (120 million), chemical abundances (up to 5 million), diffuse interstellar band analysis (0.5 million), activity indices (2 million), H-alpha equivalent widths (200 million), and further classification of spectral types (220 million) and emission-line stars (50 thousand). This catalogue is the most extensive homogeneous database of astrophysical parameters to date, and it is based uniquely on Gaia data. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2206.05864v1-abstract-full').style.display = 'none'; document.getElementById('2206.05864v1-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> 12 June, 2022; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> June 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">35 pages (incl 7 pages references, appendix, affiliations, acknowledgements), 29 figures, A&A, accepted</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> A&A 674, A26 (2023) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2203.13398">arXiv:2203.13398</a> <span> [<a href="https://arxiv.org/pdf/2203.13398">pdf</a>, <a href="https://arxiv.org/format/2203.13398">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> </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/10.21105/astro.2203.13398">10.21105/astro.2203.13398 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> V889 Her: abrupt changes in the magnetic field or differential rotation? </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Willamo%2C+T">Teemu Willamo</a>, <a href="/search/astro-ph?searchtype=author&query=Hackman%2C+T">Thomas Hackman</a>, <a href="/search/astro-ph?searchtype=author&query=Lehtinen%2C+J+J">Jyri J. Lehtinen</a>, <a href="/search/astro-ph?searchtype=author&query=Korpi-Lagg%2C+M">Maarit Korpi-Lagg</a>, <a href="/search/astro-ph?searchtype=author&query=Kochukhov%2C+O">Oleg Kochukhov</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="2203.13398v2-abstract-short" style="display: inline;"> We have applied Zeeman-Doppler imaging (ZDI) to an extensive spectropolarimetric HARPSpol data set of the magnetically active young solar analogue V889 Her, covering 35 spectra obtained during six nights in May 2011. The data set allows us to study Stokes V profiles of the star at almost identical rotational phases, separated by one or more stellar rotations. We use these data to study if the line… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2203.13398v2-abstract-full').style.display = 'inline'; document.getElementById('2203.13398v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2203.13398v2-abstract-full" style="display: none;"> We have applied Zeeman-Doppler imaging (ZDI) to an extensive spectropolarimetric HARPSpol data set of the magnetically active young solar analogue V889 Her, covering 35 spectra obtained during six nights in May 2011. The data set allows us to study Stokes V profiles of the star at almost identical rotational phases, separated by one or more stellar rotations. We use these data to study if the line profiles evolve from one rotation to the next, and find that some evolution does indeed occur. We consider two possible explanations for this: abrupt changes in the large-scale magnetic field or differential rotation. We find it quite difficult to distinguish between the two alternatives using ZDI alone. A strong differential rotation could, however, explain the changes in the line profiles, so we conclude that it must be present, and the abrupt magnetic field evolution is left uncertain. Commonly, rapidly rotating stars are assumed to have only weak differential rotation. If the strong differential rotation of V889 Her is indeed present, as has been found in other studies as well, it could indicate that the theoretical and numerical results of differential rotation still need to be revised. The rapid changes that may have occurred in the magnetic field indicate that one should be quite cautious when interpreting ZDI maps constructed from data over long time intervals. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2203.13398v2-abstract-full').style.display = 'none'; document.getElementById('2203.13398v2-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 July, 2022; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 24 March, 2022; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> March 2022. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2202.07949">arXiv:2202.07949</a> <span> [<a href="https://arxiv.org/pdf/2202.07949">pdf</a>, <a href="https://arxiv.org/format/2202.07949">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="High Energy Astrophysical Phenomena">astro-ph.HE</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/ac54b8">10.3847/1538-4357/ac54b8 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Simulating the Space Weather in the AU Mic System: Stellar Winds and Extreme Coronal Mass Ejections </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Alvarado-G%C3%B3mez%2C+J+D">Juli谩n D. Alvarado-G贸mez</a>, <a href="/search/astro-ph?searchtype=author&query=Cohen%2C+O">Ofer Cohen</a>, <a href="/search/astro-ph?searchtype=author&query=Drake%2C+J+J">Jeremy J. Drake</a>, <a href="/search/astro-ph?searchtype=author&query=Fraschetti%2C+F">Federico Fraschetti</a>, <a href="/search/astro-ph?searchtype=author&query=Poppenh%C3%A4ger%2C+K">Katja Poppenh盲ger</a>, <a href="/search/astro-ph?searchtype=author&query=Garraffo%2C+C">Cecilia Garraffo</a>, <a href="/search/astro-ph?searchtype=author&query=Chebly%2C+J">Judy Chebly</a>, <a href="/search/astro-ph?searchtype=author&query=Ilin%2C+E">Ekaterina Ilin</a>, <a href="/search/astro-ph?searchtype=author&query=Harbach%2C+L">Laura Harbach</a>, <a href="/search/astro-ph?searchtype=author&query=Kochukhov%2C+O">Oleg Kochukhov</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="2202.07949v1-abstract-short" style="display: inline;"> Two close-in planets have been recently found around the M-dwarf flare star AU Microscopii (AU Mic). These Neptune-sized planets (AU Mic b and c) seem to be located very close to the so-called "evaporation valley" in the exoplanet population, making this system an important target for studying atmospheric loss on exoplanets. This process, while mainly driven by the high-energy stellar radiation, w… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2202.07949v1-abstract-full').style.display = 'inline'; document.getElementById('2202.07949v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2202.07949v1-abstract-full" style="display: none;"> Two close-in planets have been recently found around the M-dwarf flare star AU Microscopii (AU Mic). These Neptune-sized planets (AU Mic b and c) seem to be located very close to the so-called "evaporation valley" in the exoplanet population, making this system an important target for studying atmospheric loss on exoplanets. This process, while mainly driven by the high-energy stellar radiation, will be strongly mediated by the space environment surrounding the planets. Here we present an investigation on this last area, performing 3D numerical modeling of the quiescent stellar wind from AU Mic, as well as time-dependent simulations describing the evolution of a highly energetic Coronal Mass Ejection (CME) event in this system. Observational constraints on the stellar magnetic field and properties of the eruption are incorporated in our models. We carry out qualitative and quantitative characterizations of the stellar wind, the emerging CMEs, as well as the expected steady and transient conditions along the orbit of both exoplanets. Our results predict an extreme space weather for AU Mic and its planets. This includes sub-Alfv茅nic regions for the large majority of the exoplanet orbits, very high dynamic and magnetic pressure values in quiescence (varying within $10^{2} - 10^{5}$ times the dynamic pressure experienced by the Earth), and an even harsher environment during the passage of any escaping CME associated with the frequent flaring observed in AU Mic. These space weather conditions alone pose an immense challenge for the survival of the exoplanetary atmospheres (if any) in this system. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2202.07949v1-abstract-full').style.display = 'none'; document.getElementById('2202.07949v1-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 February, 2022; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> February 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">15 Pages, 7 Figures, 2 Tables, Accepted for publication in 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/2201.05512">arXiv:2201.05512</a> <span> [<a href="https://arxiv.org/pdf/2201.05512">pdf</a>, <a href="https://arxiv.org/ps/2201.05512">ps</a>, <a href="https://arxiv.org/format/2201.05512">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="High Energy Astrophysical Phenomena">astro-ph.HE</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/stac136">10.1093/mnras/stac136 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> MOBSTER -- VI. The crucial influence of rotation on the radio magnetospheres of hot stars </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Shultz%2C+M+E">M. E. Shultz</a>, <a href="/search/astro-ph?searchtype=author&query=Owocki%2C+S+P">S. P. Owocki</a>, <a href="/search/astro-ph?searchtype=author&query=ud-Doula%2C+A">A. ud-Doula</a>, <a href="/search/astro-ph?searchtype=author&query=Biswas%2C+A">A. Biswas</a>, <a href="/search/astro-ph?searchtype=author&query=Bohlender%2C+D">D. Bohlender</a>, <a href="/search/astro-ph?searchtype=author&query=Chandra%2C+P">P. Chandra</a>, <a href="/search/astro-ph?searchtype=author&query=Das%2C+B">B. Das</a>, <a href="/search/astro-ph?searchtype=author&query=David-Uraz%2C+A">A. David-Uraz</a>, <a href="/search/astro-ph?searchtype=author&query=Khalack%2C+V">V. Khalack</a>, <a href="/search/astro-ph?searchtype=author&query=Kochukhov%2C+O">O. Kochukhov</a>, <a href="/search/astro-ph?searchtype=author&query=Landstreet%2C+J+D">J. D. Landstreet</a>, <a href="/search/astro-ph?searchtype=author&query=Leto%2C+P">P. Leto</a>, <a href="/search/astro-ph?searchtype=author&query=Monin%2C+D">D. Monin</a>, <a href="/search/astro-ph?searchtype=author&query=Neiner%2C+C">C. Neiner</a>, <a href="/search/astro-ph?searchtype=author&query=Rivinius%2C+T">Th. Rivinius</a>, <a href="/search/astro-ph?searchtype=author&query=Wade%2C+G+A">G. A. Wade</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="2201.05512v1-abstract-short" style="display: inline;"> Numerous magnetic hot stars exhibit gyrosynchrotron radio emission. The source electrons were previously thought to be accelerated to relativistic velocities in the current sheet formed in the middle magnetosphere by the wind opening magnetic field lines. However, a lack of dependence of radio luminosity on the wind power, and a strong dependence on rotation, has recently challenged this paradigm.… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2201.05512v1-abstract-full').style.display = 'inline'; document.getElementById('2201.05512v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2201.05512v1-abstract-full" style="display: none;"> Numerous magnetic hot stars exhibit gyrosynchrotron radio emission. The source electrons were previously thought to be accelerated to relativistic velocities in the current sheet formed in the middle magnetosphere by the wind opening magnetic field lines. However, a lack of dependence of radio luminosity on the wind power, and a strong dependence on rotation, has recently challenged this paradigm. We have collected all radio measurements of magnetic early-type stars available in the literature. When constraints on the magnetic field and/or the rotational period are not available, we have determined these using previously unpublished spectropolarimetric and photometric data. The result is the largest sample of magnetic stars with radio observations that has yet been analyzed: 131 stars with rotational and magnetic constraints, of which 50 are radio-bright. We confirm an obvious dependence of gyrosynchrotron radiation on rotation, and furthermore find that accounting for rotation neatly separates stars with and without detected radio emission. There is a close correlation between H$伪$ emission strength and radio luminosity. These factors suggest that radio emission may be explained by the same mechanism responsible for H$伪$ emission from centrifugal magnetospheres, i.e. centrifugal breakout (CBO), however, whereas the H$伪$-emitting magnetosphere probes the cool plasma before breakout, radio emission is a consequence of electrons accelerated in centrifugally-driven magnetic reconnection. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2201.05512v1-abstract-full').style.display = 'none'; document.getElementById('2201.05512v1-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, 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">47 pages (16 pages plus appendices), 43 figures, 9 tables, accepted for publication in MNRAS</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2201.04978">arXiv:2201.04978</a> <span> [<a href="https://arxiv.org/pdf/2201.04978">pdf</a>, <a href="https://arxiv.org/format/2201.04978">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> </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/10.1051/0004-6361/202142425">10.1051/0004-6361/202142425 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Small-scale magnetic fields of the spectroscopic binary T Tauri stars V1878 Ori and V4046 Sir </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Hahlin%2C+A">A. Hahlin</a>, <a href="/search/astro-ph?searchtype=author&query=Kochukhov%2C+O">O. Kochukhov</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="2201.04978v1-abstract-short" style="display: inline;"> Aims. The goal of this study is to investigate the small-scale magnetic fields of the two spectroscopic binary T Tauri stars V1878 Ori and V4046 Sgr. This is done to complete the observational characterisation of the surface magnetic fields of these stars because only their large-scale magnetic fields have been studied with Zeeman Doppler imaging (ZDI) so far. Methods. To investigate the small-sca… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2201.04978v1-abstract-full').style.display = 'inline'; document.getElementById('2201.04978v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2201.04978v1-abstract-full" style="display: none;"> Aims. The goal of this study is to investigate the small-scale magnetic fields of the two spectroscopic binary T Tauri stars V1878 Ori and V4046 Sgr. This is done to complete the observational characterisation of the surface magnetic fields of these stars because only their large-scale magnetic fields have been studied with Zeeman Doppler imaging (ZDI) so far. Methods. To investigate the small-scale magnetic fields, the differential Zeeman intensification of near-infrared Ti I lines was investigated using high-resolution archival spectra obtained with the ESPaDOnS spectrograph at the CFHT. In order to study the binary components separately, the spectra were disentangled by considering observations taken at different orbital phases. The Zeeman-intensification analysis was performed based on detailed polarised radiative transfer calculations aided by the Markov chain Monte Carlo inference, treating magnetic field filling factors and other stellar parameters that could affect the spectra as free parameters. Results. The obtained average magnetic field strengths of the components of V1878 Ori are 1.33 and 1.57 kG, respectively. Previous ZDI studies of V1878 Ori recovered about 14 and 20% of this magnetic field strength. For V4046 Sgr, the magnetic field strengths are 1.96 and 1.83 kG, respectively. In this case, about 12 and 9% of the total magnetic field strength was detected by ZDI. Conclusions. The small-scale magnetic field strengths obtained from Zeeman intensification are similar for the two components of each binary. This is in contrast to the large-scale magnetic fields obtained from ZDI investigations, performed using the same observations. While the large-scale field might look significantly different. This indicates that the efficiency of the magnetic dynamo is comparable for the components of the two binaries, because most energy is carreid by the small scale fields. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2201.04978v1-abstract-full').style.display = 'none'; document.getElementById('2201.04978v1-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 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">13 pages, 6 figures, accepted by A&A</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> A&A 659, A151 (2022) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2201.02554">arXiv:2201.02554</a> <span> [<a href="https://arxiv.org/pdf/2201.02554">pdf</a>, <a href="https://arxiv.org/ps/2201.02554">ps</a>, <a href="https://arxiv.org/format/2201.02554">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> </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/stac066">10.1093/mnras/stac066 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Magnetic field topology, chemical spot distributions and photometric variability of the Ap star phi Draconis </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Kochukhov%2C+O">O. Kochukhov</a>, <a href="/search/astro-ph?searchtype=author&query=Papakonstantinou%2C+N">N. Papakonstantinou</a>, <a href="/search/astro-ph?searchtype=author&query=Neiner%2C+C">C. Neiner</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="2201.02554v1-abstract-short" style="display: inline;"> The primary component of the multiple star phi Dra is one of the brightest magnetic chemically peculiar stars in the northern sky. Here we report results of a comprehensive study of the rotational photometric variability, binarity, magnetic field geometry, and surface chemical spot structure for this star. We derived a precise photometric rotational period of 1.71650213(21) d based on one year of… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2201.02554v1-abstract-full').style.display = 'inline'; document.getElementById('2201.02554v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2201.02554v1-abstract-full" style="display: none;"> The primary component of the multiple star phi Dra is one of the brightest magnetic chemically peculiar stars in the northern sky. Here we report results of a comprehensive study of the rotational photometric variability, binarity, magnetic field geometry, and surface chemical spot structure for this star. We derived a precise photometric rotational period of 1.71650213(21) d based on one year of TESS nearly continuous space observations and discovered modulation of the stellar light curve with the phase of the 127.9-d binary orbit due to the light time travel effect. We revised parameters of the binary orbit and detected spectroscopic contribution of the secondary. A tomographic mapping technique was applied to the average intensity and circular polarisation profiles derived from Narval high-resolution spectropolarimetric observations. This analysis yielded a detailed map of the global magnetic field topology together with the surface distributions of Si, Cr, and Fe abundances. Magnetic mapping demonstrates that the surface field structure of phi Dra is dominated by a distorted dipolar component with a peak field strength of 1.4 kG and a large asymmetry between the poles. Chemical maps show an enhancement of Cr, Fe and, to a lesser extent, Si in a series of spots encircling intersections of the magnetic and rotational equators. These chemical spot geometries do not directly correlate with either the local field strength or the field inclination. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2201.02554v1-abstract-full').style.display = 'none'; document.getElementById('2201.02554v1-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> 7 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">13 pages, 13 figures; accepted for publication in MNRAS</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2111.06434">arXiv:2111.06434</a> <span> [<a href="https://arxiv.org/pdf/2111.06434">pdf</a>, <a href="https://arxiv.org/format/2111.06434">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> </div> </div> <p class="title is-5 mathjax"> Ultraviolet Spectropolarimetry With Polstar: Hot Star Magnetospheres </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Shultz%2C+M+E">M. E. Shultz</a>, <a href="/search/astro-ph?searchtype=author&query=Casini%2C+R">R. Casini</a>, <a href="/search/astro-ph?searchtype=author&query=Cheung%2C+M+C+M">M. C. M. Cheung</a>, <a href="/search/astro-ph?searchtype=author&query=David-Uraz%2C+A">A. David-Uraz</a>, <a href="/search/astro-ph?searchtype=author&query=Alem%C3%A1n%2C+T+d+P">T. del Pino Alem谩n</a>, <a href="/search/astro-ph?searchtype=author&query=Erba%2C+C">C. Erba</a>, <a href="/search/astro-ph?searchtype=author&query=Folsom%2C+C+P">C. P. Folsom</a>, <a href="/search/astro-ph?searchtype=author&query=Gayley%2C+K">K. Gayley</a>, <a href="/search/astro-ph?searchtype=author&query=Ignace%2C+R">R. Ignace</a>, <a href="/search/astro-ph?searchtype=author&query=Keszthelyi%2C+Z">Z. Keszthelyi</a>, <a href="/search/astro-ph?searchtype=author&query=Kochukhov%2C+O">O. Kochukhov</a>, <a href="/search/astro-ph?searchtype=author&query=Naz%C3%A9%2C+Y">Y. Naz茅</a>, <a href="/search/astro-ph?searchtype=author&query=Neiner%2C+C">C. Neiner</a>, <a href="/search/astro-ph?searchtype=author&query=Oksala%2C+M">M. Oksala</a>, <a href="/search/astro-ph?searchtype=author&query=Petit%2C+V">V. Petit</a>, <a href="/search/astro-ph?searchtype=author&query=Scowen%2C+P+A">P. A. Scowen</a>, <a href="/search/astro-ph?searchtype=author&query=Sudnik%2C+N">N. Sudnik</a>, <a href="/search/astro-ph?searchtype=author&query=ud-Doula%2C+A">A. ud-Doula</a>, <a href="/search/astro-ph?searchtype=author&query=Vink%2C+J+S">J. S. Vink</a>, <a href="/search/astro-ph?searchtype=author&query=Wade%2C+G+A">G. A. Wade</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="2111.06434v2-abstract-short" style="display: inline;"> Polstar is a proposed NASA MIDEX space telescope that will provide high-resolution, simultaneous full-Stokes spectropolarimetry in the far ultraviolet, together with low-resolution linear polarimetry in the near ultraviolet. In this white paper, we describe the unprecedented capabilities this observatory would offer in order to obtain unique information on the magnetic and plasma properties of the… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2111.06434v2-abstract-full').style.display = 'inline'; document.getElementById('2111.06434v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2111.06434v2-abstract-full" style="display: none;"> Polstar is a proposed NASA MIDEX space telescope that will provide high-resolution, simultaneous full-Stokes spectropolarimetry in the far ultraviolet, together with low-resolution linear polarimetry in the near ultraviolet. In this white paper, we describe the unprecedented capabilities this observatory would offer in order to obtain unique information on the magnetic and plasma properties of the magnetospheres of hot stars. This would enable a test of the fundamental hypothesis that magnetospheres should act to rapidly drain angular momentum, thereby spinning the star down, whilst simultaneously reducing the net mass-loss rate. Both effects are expected to lead to dramatic differences in the evolution of magnetic vs. non-magnetic stars. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2111.06434v2-abstract-full').style.display = 'none'; document.getElementById('2111.06434v2-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 December, 2021; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 11 November, 2021; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> November 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">White paper, 40 pages</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2111.06251">arXiv:2111.06251</a> <span> [<a href="https://arxiv.org/pdf/2111.06251">pdf</a>, <a href="https://arxiv.org/format/2111.06251">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> </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/stab3320">10.1093/mnras/stab3320 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> The magnetic field and magnetosphere of Plaskett's star: A fundamental shift in our understanding of the system </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Grunhut%2C+J+H">J. H. Grunhut</a>, <a href="/search/astro-ph?searchtype=author&query=Wade%2C+G+A">G. A. Wade</a>, <a href="/search/astro-ph?searchtype=author&query=Folsom%2C+C+P">C. P. Folsom</a>, <a href="/search/astro-ph?searchtype=author&query=Neiner%2C+C">C. Neiner</a>, <a href="/search/astro-ph?searchtype=author&query=Kochukhov%2C+O">O. Kochukhov</a>, <a href="/search/astro-ph?searchtype=author&query=Alecian%2C+E">E. Alecian</a>, <a href="/search/astro-ph?searchtype=author&query=Shultz%2C+M">M. Shultz</a>, <a href="/search/astro-ph?searchtype=author&query=Petit%2C+V">V. Petit</a>, <a href="/search/astro-ph?searchtype=author&query=MiMeS%2C+t">the MiMeS</a>, <a href="/search/astro-ph?searchtype=author&query=collaborations%2C+B">BinaMIcS collaborations</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="2111.06251v1-abstract-short" style="display: inline;"> Plaskett's "star" appears to be one of a small number of short-period binary systems known to contain a hot, massive, magnetic star. Building on the 2013 discovery investigation, we combine an extensive spectropolarimetric (Stokes $V$) dataset with archival photometry and spectropolarimetry to establish the essential characteristics of the magnetic field and magnetosphere of the rapidly rotating,… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2111.06251v1-abstract-full').style.display = 'inline'; document.getElementById('2111.06251v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2111.06251v1-abstract-full" style="display: none;"> Plaskett's "star" appears to be one of a small number of short-period binary systems known to contain a hot, massive, magnetic star. Building on the 2013 discovery investigation, we combine an extensive spectropolarimetric (Stokes $V$) dataset with archival photometry and spectropolarimetry to establish the essential characteristics of the magnetic field and magnetosphere of the rapidly rotating, broad-line component of the system. We apply Least-Squares Deconvolution (LSD) to infer the longitudinal magnetic field from each Stokes $V$ spectrum. Using the timeseries of longitudinal field measurements, in combination with CoRoT photometry and equivalent width measurements of magnetospheric spectral lines, we infer the rotation period of the magnetic star to be equal to $1.21551^{+0.00028}_{-0.00034}$ d. Modeling the Stokes $V$ LSD profiles with Zeeman Doppler Imaging, we produce the first {reliable} magnetic map of an O-type star. We find a magnetic field that is predominantly dipolar, but with an important quadrupolar component, and weak higher order components. The dipolar component has an obliquity near 90 deg and a polar strength of about 850 G, while the average field strength over the entire surface is 520 G. We update the calculations of the theoretical magnetospheric parameters, and in agreement with their predictions we identify clear variability signatures of the H$伪$, H$尾$, and He II $位4686$ lines confirming the presence of a dense centrifugal magnetosphere surrounding the star. Finally, we report a lack of detection of radial velocity (RV) variations of the observed Stokes $V$ profiles, suggesting that historical reports of the large RV variations of the broad-line star's spectral lines may be spurious. This discovery may motivate a fundamental revision of the historical model of the Plaskett's star as a near-equal mass O+O binary system. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2111.06251v1-abstract-full').style.display = 'none'; document.getElementById('2111.06251v1-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 November, 2021; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> November 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">25 pages, accepted by MNRAS</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2110.06729">arXiv:2110.06729</a> <span> [<a href="https://arxiv.org/pdf/2110.06729">pdf</a>, <a href="https://arxiv.org/format/2110.06729">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> </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/10.1051/0004-6361/202141649">10.1051/0004-6361/202141649 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Zeeman-Doppler imaging of five young solar-type stars </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Willamo%2C+T">T. Willamo</a>, <a href="/search/astro-ph?searchtype=author&query=Lehtinen%2C+J+J">J. J. Lehtinen</a>, <a href="/search/astro-ph?searchtype=author&query=Hackman%2C+T">T. Hackman</a>, <a href="/search/astro-ph?searchtype=author&query=K%C3%A4pyl%C3%A4%2C+M+J">M. J. K盲pyl盲</a>, <a href="/search/astro-ph?searchtype=author&query=Kochukhov%2C+O">O. Kochukhov</a>, <a href="/search/astro-ph?searchtype=author&query=Jeffers%2C+S+V">S. V. Jeffers</a>, <a href="/search/astro-ph?searchtype=author&query=Korhonen%2C+H">H. Korhonen</a>, <a href="/search/astro-ph?searchtype=author&query=Marsden%2C+S+C">S. C. Marsden</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="2110.06729v2-abstract-short" style="display: inline;"> The magnetic activity of the Sun changes with the solar cycle. Similar cycles are found in other stars as well, but their details are not known to a similar degree. Characterising stellar magnetic cycles is important for the understanding of the stellar and solar dynamos that are driving the magnetic activity. We present spectropolarimetric observations of five young, solar-type stars, and compare… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2110.06729v2-abstract-full').style.display = 'inline'; document.getElementById('2110.06729v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2110.06729v2-abstract-full" style="display: none;"> The magnetic activity of the Sun changes with the solar cycle. Similar cycles are found in other stars as well, but their details are not known to a similar degree. Characterising stellar magnetic cycles is important for the understanding of the stellar and solar dynamos that are driving the magnetic activity. We present spectropolarimetric observations of five young, solar-type stars, and compare them to previous observations, with the aim to identify and characterise stellar equivalents of the solar cycle. We use Zeeman-Doppler imaging (ZDI) to map the surface magnetic field and brightness of our targets. The magnetic field is decomposed into spherical harmonic expansions, from which we report the strengths of the axisymmetric vs. non-axisymmetric, and poloidal vs. toroidal components, and compare them to the Rossby numbers of the stars. We present five new ZDI-maps of young, solar-type stars from Dec 2017. Of special interest is the case of V1358 Ori, that has gone through a polarity reversal between our observations and earlier ones. A less evident polarity reversal might also have occurred in HD 35296. There is a preference for more axisymmetric field, and possibly more toroidal field, for the more active stars with lower Rossby number, but a larger sample should be studied to draw any strong conclusions from this. For most of the individual stars, the amounts of toroidal and poloidal field have stayed on similar levels as in earlier observations. We find evidence for a magnetic polarity reversal having occurred in V1358 Ori. \c{hi}1 Ori could be an interesting target for future observations, with a possible short magnetic cycle of a few years. The correlation between the brightness maps and the magnetic field is mostly poor, which could indicate the presence of small-scale magnetic features of different polarities, that cancel each other out, and are not resolved in our maps. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2110.06729v2-abstract-full').style.display = 'none'; document.getElementById('2110.06729v2-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 May, 2022; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 13 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">Journal ref:</span> A&A 659, A71 (2022) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2110.06000">arXiv:2110.06000</a> <span> [<a href="https://arxiv.org/pdf/2110.06000">pdf</a>, <a href="https://arxiv.org/format/2110.06000">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> </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/10.1051/0004-6361/202141525">10.1051/0004-6361/202141525 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Time evolution of magnetic activity cycles in young suns: The curious case of kappa Ceti </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Saikia%2C+S+B">S. Boro Saikia</a>, <a href="/search/astro-ph?searchtype=author&query=Lueftinger%2C+T">T. Lueftinger</a>, <a href="/search/astro-ph?searchtype=author&query=Folsom%2C+C+P">C. P. Folsom</a>, <a href="/search/astro-ph?searchtype=author&query=Antonova%2C+A">A. Antonova</a>, <a href="/search/astro-ph?searchtype=author&query=Alecian%2C+E">E. Alecian</a>, <a href="/search/astro-ph?searchtype=author&query=Donati%2C+J+-">J. -F. Donati</a>, <a href="/search/astro-ph?searchtype=author&query=Guedel%2C+M">M. Guedel</a>, <a href="/search/astro-ph?searchtype=author&query=Hall%2C+J+C">J. C. Hall</a>, <a href="/search/astro-ph?searchtype=author&query=Jeffers%2C+S+V">S. V. Jeffers</a>, <a href="/search/astro-ph?searchtype=author&query=Kochukhov%2C+O">O. Kochukhov</a>, <a href="/search/astro-ph?searchtype=author&query=Marsden%2C+S+C">S. C. Marsden</a>, <a href="/search/astro-ph?searchtype=author&query=Metodieva%2C+Y+T">Y. T. Metodieva</a>, <a href="/search/astro-ph?searchtype=author&query=Mittag%2C+M">M. Mittag</a>, <a href="/search/astro-ph?searchtype=author&query=Morin%2C+J">J. Morin</a>, <a href="/search/astro-ph?searchtype=author&query=Perdelwitz%2C+V">V. Perdelwitz</a>, <a href="/search/astro-ph?searchtype=author&query=Petit%2C+P">P. Petit</a>, <a href="/search/astro-ph?searchtype=author&query=Schmid%2C+M">M. Schmid</a>, <a href="/search/astro-ph?searchtype=author&query=Vidotto%2C+A+A">A. A. Vidotto</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="2110.06000v1-abstract-short" style="display: inline;"> A detailed investigation of the magnetic properties of young Sun-like stars can provide valuable information on our Sun's magnetic past and its impact on the early Earth. We determine the properties of the moderately rotating young Sun-like star kappa Ceti's magnetic and activity cycles using 50 years of chromospheric activity data and six epochs of spectropolarimetric observations. The chromosphe… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2110.06000v1-abstract-full').style.display = 'inline'; document.getElementById('2110.06000v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2110.06000v1-abstract-full" style="display: none;"> A detailed investigation of the magnetic properties of young Sun-like stars can provide valuable information on our Sun's magnetic past and its impact on the early Earth. We determine the properties of the moderately rotating young Sun-like star kappa Ceti's magnetic and activity cycles using 50 years of chromospheric activity data and six epochs of spectropolarimetric observations. The chromospheric activity was determined by measuring the flux in the Ca II H and K lines. A generalised Lomb-Scargle periodogram and a wavelet decomposition were used on the chromospheric activity data to establish the associated periodicities. The vector magnetic field of the star was reconstructed using the technique of Zeeman Doppler imaging on the spectropolarimetric observations. Our period analysis algorithms detect a 3.1 year chromospheric cycle in addition to the star's well-known ~6 year cycle period. Although the two cycle periods have an approximate 1:2 ratio, they exhibit an unusual temporal evolution. Additionally, the spectropolarimetric data analysis shows polarity reversals of the star's large-scale magnetic field, suggesting a ~10 year magnetic or Hale cycle. The unusual evolution of the star's chromospheric cycles and their lack of a direct correlation with the magnetic cycle establishes kappa Ceti as a curious young Sun. Such complex evolution of magnetic activity could be synonymous with moderately active young Suns, which is an evolutionary path that our own Sun could have taken. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2110.06000v1-abstract-full').style.display = 'none'; document.getElementById('2110.06000v1-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> 12 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">15 pages including appendices, accepted for publication in A&A</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2109.04043">arXiv:2109.04043</a> <span> [<a href="https://arxiv.org/pdf/2109.04043">pdf</a>, <a href="https://arxiv.org/format/2109.04043">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> </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/ac2576">10.3847/1538-4357/ac2576 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Discovery of eight 'Main-sequence Radio Pulse emitters' using the GMRT: clues to the onset of coherent radio emission in hot magnetic stars </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Das%2C+B">Barnali Das</a>, <a href="/search/astro-ph?searchtype=author&query=Chandra%2C+P">Poonam Chandra</a>, <a href="/search/astro-ph?searchtype=author&query=Shultz%2C+M+E">Matt E. Shultz</a>, <a href="/search/astro-ph?searchtype=author&query=Wade%2C+G+A">Gregg A. Wade</a>, <a href="/search/astro-ph?searchtype=author&query=Sikora%2C+J">James Sikora</a>, <a href="/search/astro-ph?searchtype=author&query=Kochukhov%2C+O">Oleg Kochukhov</a>, <a href="/search/astro-ph?searchtype=author&query=Neiner%2C+C">Coralie Neiner</a>, <a href="/search/astro-ph?searchtype=author&query=Oksala%2C+M+E">Mary E. Oksala</a>, <a href="/search/astro-ph?searchtype=author&query=Alecian%2C+E">Evelyne Alecian</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="2109.04043v1-abstract-short" style="display: inline;"> 'Main-sequence radio pulse-emitters' (MRPs) are magnetic early-type stars from which periodic radio pulses, produced via electron cyclotron maser emission (ECME), are observed. Despite the fact that these stars can naturally offer suitable conditions for triggering ECME, only seven such stars have been reported so far within a span of more than two decades. In this paper, we report the discovery o… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2109.04043v1-abstract-full').style.display = 'inline'; document.getElementById('2109.04043v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2109.04043v1-abstract-full" style="display: none;"> 'Main-sequence radio pulse-emitters' (MRPs) are magnetic early-type stars from which periodic radio pulses, produced via electron cyclotron maser emission (ECME), are observed. Despite the fact that these stars can naturally offer suitable conditions for triggering ECME, only seven such stars have been reported so far within a span of more than two decades. In this paper, we report the discovery of eight more MRPs, thus more than doubling the sample size of such objects. These discoveries are the result of our sub-GHz observation program using the Giant Metrewave Radio Telescope over the years 2015-2021. Adding these stars to the previously known MRPs, we infer that at least 32 percent of the magnetic hot stars exhibit this phenomenon, thus suggesting that observation of ECME is not a rare phenomenon. The significantly larger sample of MRPs allows us for the first time to perform a statistical analysis comparing their physical properties. We present an empirical relation that can be used to predict whether a magnetic hot star is likely to produce ECME. Our preliminary analysis suggests that the physical parameters that play the primary role in the efficiency of the phenomenon are the maximum surface magnetic field strength and the surface temperature. In addition, we present strong evidence of the influence of the plasma density distribution on ECME pulse profiles. Results of this kind further motivate the search for MRPs as a robust characterization of the relation between observed ECME properties and stellar physical parameters can only be achieved with a large sample. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2109.04043v1-abstract-full').style.display = 'none'; document.getElementById('2109.04043v1-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 September, 2021; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> September 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">24 pages, 11 figures, accepted for publication in the 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/2108.09266">arXiv:2108.09266</a> <span> [<a href="https://arxiv.org/pdf/2108.09266">pdf</a>, <a href="https://arxiv.org/format/2108.09266">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="Computer Vision and Pattern Recognition">cs.CV</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/10.1051/0004-6361/202142027">10.1051/0004-6361/202142027 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Approximate Bayesian Neural Doppler Imaging </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Ramos%2C+A+A">A. Asensio Ramos</a>, <a href="/search/astro-ph?searchtype=author&query=Baso%2C+C+D">C. Diaz Baso</a>, <a href="/search/astro-ph?searchtype=author&query=Kochukhov%2C+O">O. Kochukhov</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="2108.09266v1-abstract-short" style="display: inline;"> The non-uniform surface temperature distribution of rotating active stars is routinely mapped with the Doppler Imaging technique. Inhomogeneities in the surface produce features in high-resolution spectroscopic observations that shift in wavelength depending on their position on the visible hemisphere. The inversion problem has been systematically solved using maximum a-posteriori regularized meth… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2108.09266v1-abstract-full').style.display = 'inline'; document.getElementById('2108.09266v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2108.09266v1-abstract-full" style="display: none;"> The non-uniform surface temperature distribution of rotating active stars is routinely mapped with the Doppler Imaging technique. Inhomogeneities in the surface produce features in high-resolution spectroscopic observations that shift in wavelength depending on their position on the visible hemisphere. The inversion problem has been systematically solved using maximum a-posteriori regularized methods assuming smoothness or maximum entropy. Our aim in this work is to solve the full Bayesian inference problem, by providing access to the posterior distribution of the surface temperature in the star. We use amortized neural posterior estimation to produce a model that approximates the high-dimensional posterior distribution for spectroscopic observations of selected spectral ranges sampled at arbitrary rotation phases. The posterior distribution is approximated with conditional normalizing flows, which are flexible, tractable and easy to sample approximations to arbitrary distributions. When conditioned on the spectroscopic observations, they provide a very efficient way of obtaining samples from the posterior distribution. The conditioning on observations is obtained through the use of Transformer encoders, which can deal with arbitrary wavelength sampling and rotation phases. Our model can produce thousands of posterior samples per second. Our validation of the model for very high signal-to-noise observations shows that it correctly approximates the posterior, although with some overestimation of the broadening. We apply the model to the moderately fast rotator II Peg, producing the first Bayesian map of its temperature inhomogenities. We conclude that conditional normalizing flows are a very promising tool to carry out approximate Bayesian inference in more complex problems in stellar physics, like constraining the magnetic properties. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2108.09266v1-abstract-full').style.display = 'none'; document.getElementById('2108.09266v1-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 August, 2021; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> August 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">14 pages, 10 figures, submitted to A&A</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2108.01088">arXiv:2108.01088</a> <span> [<a href="https://arxiv.org/pdf/2108.01088">pdf</a>, <a href="https://arxiv.org/format/2108.01088">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> </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/ac1f19">10.3847/1538-4357/ac1f19 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Magnetic and Rotational Evolution of $蟻$ CrB from Asteroseismology with TESS </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Metcalfe%2C+T+S">Travis S. Metcalfe</a>, <a href="/search/astro-ph?searchtype=author&query=van+Saders%2C+J+L">Jennifer L. van Saders</a>, <a href="/search/astro-ph?searchtype=author&query=Basu%2C+S">Sarbani Basu</a>, <a href="/search/astro-ph?searchtype=author&query=Buzasi%2C+D">Derek Buzasi</a>, <a href="/search/astro-ph?searchtype=author&query=Drake%2C+J+J">Jeremy J. Drake</a>, <a href="/search/astro-ph?searchtype=author&query=Egeland%2C+R">Ricky Egeland</a>, <a href="/search/astro-ph?searchtype=author&query=Huber%2C+D">Daniel Huber</a>, <a href="/search/astro-ph?searchtype=author&query=Saar%2C+S+H">Steven H. Saar</a>, <a href="/search/astro-ph?searchtype=author&query=Stassun%2C+K+G">Keivan G. Stassun</a>, <a href="/search/astro-ph?searchtype=author&query=Ball%2C+W+H">Warrick H. Ball</a>, <a href="/search/astro-ph?searchtype=author&query=Campante%2C+T+L">Tiago L. Campante</a>, <a href="/search/astro-ph?searchtype=author&query=Finley%2C+A+J">Adam J. Finley</a>, <a href="/search/astro-ph?searchtype=author&query=Kochukhov%2C+O">Oleg Kochukhov</a>, <a href="/search/astro-ph?searchtype=author&query=Mathur%2C+S">Savita Mathur</a>, <a href="/search/astro-ph?searchtype=author&query=Reinhold%2C+T">Timo Reinhold</a>, <a href="/search/astro-ph?searchtype=author&query=See%2C+V">Victor See</a>, <a href="/search/astro-ph?searchtype=author&query=Baliunas%2C+S">Sallie Baliunas</a>, <a href="/search/astro-ph?searchtype=author&query=Soon%2C+W">Willie Soon</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="2108.01088v2-abstract-short" style="display: inline;"> During the first half of main-sequence lifetimes, the evolution of rotation and magnetic activity in solar-type stars appears to be strongly coupled. Recent observations suggest that rotation rates evolve much more slowly beyond middle-age, while stellar activity continues to decline. We aim to characterize this mid-life transition by combining archival stellar activity data from the Mount Wilson… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2108.01088v2-abstract-full').style.display = 'inline'; document.getElementById('2108.01088v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2108.01088v2-abstract-full" style="display: none;"> During the first half of main-sequence lifetimes, the evolution of rotation and magnetic activity in solar-type stars appears to be strongly coupled. Recent observations suggest that rotation rates evolve much more slowly beyond middle-age, while stellar activity continues to decline. We aim to characterize this mid-life transition by combining archival stellar activity data from the Mount Wilson Observatory with asteroseismology from the Transiting Exoplanet Survey Satellite (TESS). For two stars on opposite sides of the transition (88 Leo and $蟻$ CrB), we independently assess the mean activity levels and rotation periods previously reported in the literature. For the less active star ($蟻$ CrB), we detect solar-like oscillations from TESS photometry, and we obtain precise stellar properties from asteroseismic modeling. We derive updated X-ray luminosities for both stars to estimate their mass-loss rates, and we use previously published constraints on magnetic morphology to model the evolutionary change in magnetic braking torque. We then attempt to match the observations with rotational evolution models, assuming either standard spin-down or weakened magnetic braking. We conclude that the asteroseismic age of $蟻$ CrB is consistent with the expected evolution of its mean activity level, and that weakened braking models can more readily explain its relatively fast rotation rate. Future spectropolarimetric observations across a range of spectral types promise to further characterize the shift in magnetic morphology that apparently drives this mid-life transition in solar-type stars. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2108.01088v2-abstract-full').style.display = 'none'; document.getElementById('2108.01088v2-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 August, 2021; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 2 August, 2021; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> August 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 of text including 6 figures and 2 tables. ApJ accepted</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Astrophys. J. 921, 122 (2021) </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=Kochukhov%2C+O&start=50" class="pagination-next" >Next </a> <ul class="pagination-list"> <li> <a href="/search/?searchtype=author&query=Kochukhov%2C+O&start=0" class="pagination-link is-current" aria-label="Goto page 1">1 </a> </li> <li> <a href="/search/?searchtype=author&query=Kochukhov%2C+O&start=50" class="pagination-link " aria-label="Page 2" aria-current="page">2 </a> </li> <li> <a href="/search/?searchtype=author&query=Kochukhov%2C+O&start=100" class="pagination-link " aria-label="Page 3" aria-current="page">3 </a> </li> <li> <a href="/search/?searchtype=author&query=Kochukhov%2C+O&start=150" class="pagination-link " aria-label="Page 4" aria-current="page">4 </a> </li> <li> <a 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