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breathe-horizontal" role="navigation" aria-label="pagination"> <a href="" class="pagination-previous is-invisible">Previous </a> <a href="/search/?searchtype=author&query=G%C3%BCttler%2C+C&start=50" class="pagination-next" >Next </a> <ul class="pagination-list"> <li> <a href="/search/?searchtype=author&query=G%C3%BCttler%2C+C&start=0" class="pagination-link is-current" aria-label="Goto page 1">1 </a> </li> <li> <a href="/search/?searchtype=author&query=G%C3%BCttler%2C+C&start=50" class="pagination-link " aria-label="Page 2" aria-current="page">2 </a> </li> </ul> </nav> <ol class="breathe-horizontal" start="1"> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2401.10051">arXiv:2401.10051</a> <span> [<a href="https://arxiv.org/pdf/2401.10051">pdf</a>, <a href="https://arxiv.org/format/2401.10051">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/ad18d9">10.3847/2041-8213/ad18d9 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Diurnal ejection of boulder clusters on comet 67P lasting beyond 3 AU </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Shi%2C+X">Xian Shi</a>, <a href="/search/?searchtype=author&query=Hu%2C+X">Xuanyu Hu</a>, <a href="/search/?searchtype=author&query=Agarwal%2C+J">Jessica Agarwal</a>, <a href="/search/?searchtype=author&query=G%C3%BCttler%2C+C">Carsten G眉ttler</a>, <a href="/search/?searchtype=author&query=Rose%2C+M">Martin Rose</a>, <a href="/search/?searchtype=author&query=Keller%2C+H+U">Horst Uwe Keller</a>, <a href="/search/?searchtype=author&query=Fulle%2C+M">Marco Fulle</a>, <a href="/search/?searchtype=author&query=Deller%2C+J">Jakob Deller</a>, <a href="/search/?searchtype=author&query=Sierks%2C+H">Holger Sierks</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="2401.10051v1-abstract-short" style="display: inline;"> Ejection of large boulder-like debris is a vigorous form of cometary activity that is unlikely induced by water ice out-gassing alone but rather associated with the sublimation of super-volatile ices. Though perceived on several comets, actual pattern and mechanism of such activity are still unclear. Here we report on a specialized observation of ejections of decimeter- to meter-sized boulders on… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2401.10051v1-abstract-full').style.display = 'inline'; document.getElementById('2401.10051v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2401.10051v1-abstract-full" style="display: none;"> Ejection of large boulder-like debris is a vigorous form of cometary activity that is unlikely induced by water ice out-gassing alone but rather associated with the sublimation of super-volatile ices. Though perceived on several comets, actual pattern and mechanism of such activity are still unclear. Here we report on a specialized observation of ejections of decimeter- to meter-sized boulders on comet 67P/Churyumov-Gerasimenko outbound between 2.5 and 3.3 AU from the Sun. With a common source region, these events recurred in local morning. The boulders of elongated shapes were ejected in clusters at low inclinations comparable to the solar elevation below 40 degrees at the time. We show that these chunks could be propelled by the surrounding, asymmetric gas field that produced a distinct lateral acceleration. Possibly both water and carbon dioxide have contributed to their mobilization, while the season and local topography are among deciding factors. The mechanisms for sustaining regular activity of comets at large heliocentric distances are likely more diverse and intricate than previously thought. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2401.10051v1-abstract-full').style.display = 'none'; document.getElementById('2401.10051v1-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 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">Journal ref:</span> ApJL 961 L16 (2024) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2307.03514">arXiv:2307.03514</a> <span> [<a href="https://arxiv.org/pdf/2307.03514">pdf</a>, <a href="https://arxiv.org/format/2307.03514">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="Soft Condensed Matter">cond-mat.soft</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/stad2229">10.1093/mnras/stad2229 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Simulation and experiment of gas diffusion in a granular bed </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=G%C3%BCttler%2C+C">Carsten G眉ttler</a>, <a href="/search/?searchtype=author&query=Rose%2C+M">Martin Rose</a>, <a href="/search/?searchtype=author&query=Sierks%2C+H">Holger Sierks</a>, <a href="/search/?searchtype=author&query=Macher%2C+W">Wolfgang Macher</a>, <a href="/search/?searchtype=author&query=Zivithal%2C+S">Stephan Zivithal</a>, <a href="/search/?searchtype=author&query=Blum%2C+J">J眉rgen Blum</a>, <a href="/search/?searchtype=author&query=Laddha%2C+S">Sunny Laddha</a>, <a href="/search/?searchtype=author&query=Gundlach%2C+B">Bastian Gundlach</a>, <a href="/search/?searchtype=author&query=Kargl%2C+G">G眉nter Kargl</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="2307.03514v1-abstract-short" style="display: inline;"> The diffusion of gas through porous material is important to understand the physical processes underlying cometary activity. We study the diffusion of a rarefied gas (Knudsen regime) through a packed bed of monodisperse spheres via experiments and numerical modelling, providing an absolute value of the diffusion coefficient and compare it to published analytical models. The experiments are designe… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2307.03514v1-abstract-full').style.display = 'inline'; document.getElementById('2307.03514v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2307.03514v1-abstract-full" style="display: none;"> The diffusion of gas through porous material is important to understand the physical processes underlying cometary activity. We study the diffusion of a rarefied gas (Knudsen regime) through a packed bed of monodisperse spheres via experiments and numerical modelling, providing an absolute value of the diffusion coefficient and compare it to published analytical models. The experiments are designed to be directly comparable to numerical simulations, by using precision steel beads, simple geometries, and a trade-off of the sample size between small boundary effects and efficient computation. For direct comparison, the diffusion coefficient is determined in Direct Simulation Monte Carlo (DSMC) simulations, yielding a good match with experiments. This model is further-on used on a microscopic scale, which cannot be studied in experiments, to determine the mean path of gas molecules and its distribution, and compare it against an analytical model. Scaling with sample properties (particle size, porosity) and gas properties (molecular mass, temperature) is consistent with analytical models. As predicted by these, results are very sensitive on sample porosity and we find that a tortuosity $q(\varepsilon)$ depending linearly on the porosity $\varepsilon$ can well reconcile the analytical model with experiments and simulations. Mean paths of molecules are close to those described in the literature, but their distribution deviates from the expectation for small path lengths. The provided diffusion coefficients and scaling laws are directly applicable to thermophysical models of idealised cometary material. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2307.03514v1-abstract-full').style.display = 'none'; document.getElementById('2307.03514v1-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 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">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/2210.08134">arXiv:2210.08134</a> <span> [<a href="https://arxiv.org/pdf/2210.08134">pdf</a>, <a href="https://arxiv.org/format/2210.08134">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/10.1093/mnras/stac2560">10.1093/mnras/stac2560 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> CO2-driven surface changes in the Hapi region on Comet 67P/Churyumov-Gerasimenko </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Davidsson%2C+B+J+R">Bj枚rn J. R. Davidsson</a>, <a href="/search/?searchtype=author&query=Schloerb%2C+F+P">F. Peter Schloerb</a>, <a href="/search/?searchtype=author&query=Fornasier%2C+S">Sonia Fornasier</a>, <a href="/search/?searchtype=author&query=Oklay%2C+N">Nilda Oklay</a>, <a href="/search/?searchtype=author&query=Guti%C3%A9rrez%2C+P+J">Pedro J. Guti茅rrez</a>, <a href="/search/?searchtype=author&query=Buratti%2C+B+J">Bonnie J. Buratti</a>, <a href="/search/?searchtype=author&query=Chmielewski%2C+A+B">Artur B. Chmielewski</a>, <a href="/search/?searchtype=author&query=Gulkis%2C+S">Samuel Gulkis</a>, <a href="/search/?searchtype=author&query=Hofstadter%2C+M+D">Mark D. Hofstadter</a>, <a href="/search/?searchtype=author&query=Keller%2C+H+U">H. Uwe Keller</a>, <a href="/search/?searchtype=author&query=Sierks%2C+H">Holger Sierks</a>, <a href="/search/?searchtype=author&query=G%C3%BCttler%2C+C">Carsten G眉ttler</a>, <a href="/search/?searchtype=author&query=K%C3%BCppers%2C+M">Michael K眉ppers</a>, <a href="/search/?searchtype=author&query=Rickman%2C+H">Hans Rickman</a>, <a href="/search/?searchtype=author&query=Choukroun%2C+M">Mathieu Choukroun</a>, <a href="/search/?searchtype=author&query=Lee%2C+S">Seungwon Lee</a>, <a href="/search/?searchtype=author&query=Lellouch%2C+E">Emmanuel Lellouch</a>, <a href="/search/?searchtype=author&query=Lethuillier%2C+A">Anthony Lethuillier</a>, <a href="/search/?searchtype=author&query=Da+Deppo%2C+V">Vania Da Deppo</a>, <a href="/search/?searchtype=author&query=Groussin%2C+O">Olivier Groussin</a>, <a href="/search/?searchtype=author&query=K%C3%BChrt%2C+E">Ekkehard K眉hrt</a>, <a href="/search/?searchtype=author&query=Thomas%2C+N">Nicolas Thomas</a>, <a href="/search/?searchtype=author&query=Tubiana%2C+C">Cecilia Tubiana</a>, <a href="/search/?searchtype=author&query=El-Maarry%2C+M+R">M. Ramy El-Maarry</a>, <a href="/search/?searchtype=author&query=La+Forgia%2C+F">Fiorangela La Forgia</a> , et al. (2 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="2210.08134v1-abstract-short" style="display: inline;"> Between 2014 December 31 and 2015 March 17, the OSIRIS cameras on Rosetta documented the growth of a 140m wide and 0.5m deep depression in the Hapi region on Comet 67P/Churyumov-Gerasimenko. This shallow pit is one of several that later formed elsewhere on the comet, all in smooth terrain that primarily is the result of airfall of coma particles. We have compiled observations of this region in Hap… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2210.08134v1-abstract-full').style.display = 'inline'; document.getElementById('2210.08134v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2210.08134v1-abstract-full" style="display: none;"> Between 2014 December 31 and 2015 March 17, the OSIRIS cameras on Rosetta documented the growth of a 140m wide and 0.5m deep depression in the Hapi region on Comet 67P/Churyumov-Gerasimenko. This shallow pit is one of several that later formed elsewhere on the comet, all in smooth terrain that primarily is the result of airfall of coma particles. We have compiled observations of this region in Hapi by the microwave instrument MIRO on Rosetta, acquired during October and November 2014. We use thermophysical and radiative transfer models in order to reproduce the MIRO observations. This allows us to place constraints on the thermal inertia, diffusivity, chemical composition, stratification, extinction coefficients, and scattering properties of the surface material, and how they evolved during the months prior to pit formation. The results are placed in context through long-term comet nucleus evolution modelling. We propose that: 1) MIRO observes signatures that are consistent with a solid-state greenhouse effect in airfall material; 2) CO2 ice is sufficiently close to the surface to have a measurable effect on MIRO antenna temperatures, and likely is responsible for the pit formation in Hapi observed by OSIRIS; 3) the pressure at the CO2 sublimation front is sufficiently strong to expel dust and water ice outwards, and to compress comet material inwards, thereby causing the near-surface compaction observed by CONSERT, SESAME, and groundbased radar, manifested as the "consolidated terrain" texture observed by OSIRIS. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2210.08134v1-abstract-full').style.display = 'none'; document.getElementById('2210.08134v1-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 October, 2022; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> October 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">32 pages, 41 figures. This is a pre-copyedited, author-produced PDF of an article accepted for publication in MNRAS following peer review</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Mon. Not. R. Astron. Soc. 516, 6009-6040 (2022) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2110.05832">arXiv:2110.05832</a> <span> [<a href="https://arxiv.org/pdf/2110.05832">pdf</a>, <a href="https://arxiv.org/format/2110.05832">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="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/10.1093/mnras/stac1734">10.1093/mnras/stac1734 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Cometary dust analogues for physics experiments </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Lethuillier%2C+A">A. Lethuillier</a>, <a href="/search/?searchtype=author&query=Feller%2C+C">C. Feller</a>, <a href="/search/?searchtype=author&query=Kaufmann%2C+E">E. Kaufmann</a>, <a href="/search/?searchtype=author&query=Becerra%2C+P">P. Becerra</a>, <a href="/search/?searchtype=author&query=H%C3%A4nni%2C+N">N. H盲nni</a>, <a href="/search/?searchtype=author&query=Diethelm%2C+R">R. Diethelm</a>, <a href="/search/?searchtype=author&query=Kreuzig%2C+C">C. Kreuzig</a>, <a href="/search/?searchtype=author&query=Gundlach%2C+B">B. Gundlach</a>, <a href="/search/?searchtype=author&query=Blum%2C+J">J. Blum</a>, <a href="/search/?searchtype=author&query=Pommerol%2C+A">A. Pommerol</a>, <a href="/search/?searchtype=author&query=Kargl%2C+G">G. Kargl</a>, <a href="/search/?searchtype=author&query=K%C3%BChrt%2C+E">E. K眉hrt</a>, <a href="/search/?searchtype=author&query=Capelo%2C+H">H. Capelo</a>, <a href="/search/?searchtype=author&query=Haack%2C+D">D. Haack</a>, <a href="/search/?searchtype=author&query=Zhang%2C+X">X. Zhang</a>, <a href="/search/?searchtype=author&query=Knollenberg%2C+J">J. Knollenberg</a>, <a href="/search/?searchtype=author&query=Molinski%2C+N+S">N. S. Molinski</a>, <a href="/search/?searchtype=author&query=Gilke%2C+T">T. Gilke</a>, <a href="/search/?searchtype=author&query=Sierks%2C+H">H. Sierks</a>, <a href="/search/?searchtype=author&query=Tiefenbacher%2C+P">P. Tiefenbacher</a>, <a href="/search/?searchtype=author&query=G%C3%BCttler%2C+C">C. G眉ttler</a>, <a href="/search/?searchtype=author&query=Otto%2C+K+A">K. A. Otto</a>, <a href="/search/?searchtype=author&query=Bischoff%2C+D">D. Bischoff</a>, <a href="/search/?searchtype=author&query=Schweighart%2C+M">M. Schweighart</a>, <a href="/search/?searchtype=author&query=Hagermann%2C+A">A. Hagermann</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="2110.05832v1-abstract-short" style="display: inline;"> The CoPhyLab (Cometary Physics Laboratory) project is designed to study the physics of comets through a series of earth-based experiments. For these experiments, a dust analogue was created with physical properties comparable to those of the non-volatile dust found on comets. This "CoPhyLab dust" is planned to be mixed with water and CO$_2$ ice and placed under cometary conditions in vacuum chambe… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2110.05832v1-abstract-full').style.display = 'inline'; document.getElementById('2110.05832v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2110.05832v1-abstract-full" style="display: none;"> The CoPhyLab (Cometary Physics Laboratory) project is designed to study the physics of comets through a series of earth-based experiments. For these experiments, a dust analogue was created with physical properties comparable to those of the non-volatile dust found on comets. This "CoPhyLab dust" is planned to be mixed with water and CO$_2$ ice and placed under cometary conditions in vacuum chambers to study the physical processes taking place on the nuclei of comets. In order to develop this dust analogue, we mixed two components representative for the non-volatile materials present in cometary nuclei. We chose silica dust as representative for the mineral phase and charcoal for the organic phase, which also acts as a darkening agent. In this paper, we provide an overview of known cometary analogues before presenting measurements of eight physical properties of different mixtures of the two materials and a comparison of these measurements with known cometary values. The physical properties of interest are: particle size, density, gas permeability, spectrophotometry, mechanical, thermal and electrical properties. We found that the analogue dust that matches the highest number of physical properties of cometary materials consists of a mixture of either 60\%/40\% or 70\%/30\% of silica dust/charcoal by mass. These best-fit dust analogue will be used in future CoPhyLab experiments. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2110.05832v1-abstract-full').style.display = 'none'; document.getElementById('2110.05832v1-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> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2104.10950">arXiv:2104.10950</a> <span> [<a href="https://arxiv.org/pdf/2104.10950">pdf</a>, <a href="https://arxiv.org/format/2104.10950">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/10.1093/mnras/stab1152">10.1093/mnras/stab1152 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Observational constraints to the dynamics of dust particles in the coma of comet 67P/Churyumov-Gerasimenko </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Frattin%2C+E">Elisa Frattin</a>, <a href="/search/?searchtype=author&query=Bertini%2C+I">I. Bertini</a>, <a href="/search/?searchtype=author&query=Ivanovski%2C+S+L">S. L. Ivanovski</a>, <a href="/search/?searchtype=author&query=Marzari%2C+F">F. Marzari</a>, <a href="/search/?searchtype=author&query=Fulle%2C+M">M. Fulle</a>, <a href="/search/?searchtype=author&query=Zakharov%2C+V+V">V. V. Zakharov</a>, <a href="/search/?searchtype=author&query=Moreno%2C+F">F. Moreno</a>, <a href="/search/?searchtype=author&query=Naletto%2C+G">G. Naletto</a>, <a href="/search/?searchtype=author&query=Lazzarin%2C+M">M. Lazzarin</a>, <a href="/search/?searchtype=author&query=Cambianica%2C+P">P. Cambianica</a>, <a href="/search/?searchtype=author&query=Cremonese%2C+G">G. Cremonese</a>, <a href="/search/?searchtype=author&query=Ferrari%2C+S">S. Ferrari</a>, <a href="/search/?searchtype=author&query=Ferri%2C+F">F. Ferri</a>, <a href="/search/?searchtype=author&query=Guettler%2C+C">C. Guettler</a>, <a href="/search/?searchtype=author&query=La+Forgia%2C+F">F. La Forgia</a>, <a href="/search/?searchtype=author&query=Lucchetti%2C+A">A. Lucchetti</a>, <a href="/search/?searchtype=author&query=Pajola%2C+M">M. Pajola</a>, <a href="/search/?searchtype=author&query=Penasa%2C+L">L. Penasa</a>, <a href="/search/?searchtype=author&query=Rotundi%2C+A">A. Rotundi</a>, <a href="/search/?searchtype=author&query=Sierks%2C+H">H. Sierks</a>, <a href="/search/?searchtype=author&query=Tubiana%2C+C">C. Tubiana</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="2104.10950v1-abstract-short" style="display: inline;"> In this work we aim to characterise the dust motion in the inner coma of comet 67P/Churyumov- Gerasimenko to provide constraints for theoretical 3D coma models. The OSIRIS camera onboard the Rosetta mission was able for the first time to acquire images of single dust particles from inside the cometary coma, very close to the nucleus. We analyse a large number of particles, performing a significant… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2104.10950v1-abstract-full').style.display = 'inline'; document.getElementById('2104.10950v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2104.10950v1-abstract-full" style="display: none;"> In this work we aim to characterise the dust motion in the inner coma of comet 67P/Churyumov- Gerasimenko to provide constraints for theoretical 3D coma models. The OSIRIS camera onboard the Rosetta mission was able for the first time to acquire images of single dust particles from inside the cometary coma, very close to the nucleus. We analyse a large number of particles, performing a significant statistic of their behaviour during the post perihelion period, when the spacecraft covered distances from the nucleus ranging between 80 and 400 km. We describe the particle trajectories, investigating their orientation and finding highly radial motion with respect to the nucleus. Then, from the particle brightness profiles, we derive a particle rotational frequency of v < 3.6 Hz, revealing that they are slow rotators and do not undergo fragmentation. We use scattering models to compare the observed spectral radiance of the particles with the simulated ones in order to estimate their size, finding values that range from millimetres up to centimetres. The statistics performed in this paper provide useful parameters to constrain the cometary coma dynamical models. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2104.10950v1-abstract-full').style.display = 'none'; document.getElementById('2104.10950v1-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 April, 2021; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> April 2021. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2008.03180">arXiv:2008.03180</a> <span> [<a href="https://arxiv.org/pdf/2008.03180">pdf</a>, <a href="https://arxiv.org/format/2008.03180">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"> Spectrophotometric characterization of the Philae landing site and surroundings with the ROSETTA/OSIRIS cameras </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Van+Hoang%2C+H">Hong Van Hoang</a>, <a href="/search/?searchtype=author&query=Fornasier%2C+S">S. Fornasier</a>, <a href="/search/?searchtype=author&query=Quirico%2C+E">E. Quirico</a>, <a href="/search/?searchtype=author&query=Hasselmann%2C+P+H">P. H. Hasselmann</a>, <a href="/search/?searchtype=author&query=Barucci%2C+M+A">M. A. Barucci</a>, <a href="/search/?searchtype=author&query=Sierks%2C+H">H. Sierks</a>, <a href="/search/?searchtype=author&query=Tubiana%2C+C">C. Tubiana</a>, <a href="/search/?searchtype=author&query=G%C3%BCttler%2C+C">C. G眉ttler</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="2008.03180v1-abstract-short" style="display: inline;"> We investigate Abydos, the final landing site of the Philae lander after its eventful landing from the Rosetta spacecraft on comet 67P/Churyumov-Gerasimenko on 12 November 2014. Over 1000 OSIRIS level 3B images were analysed, which cover the August 2014 to September 2016 timeframe, with spatial resolution ranging from 7.6 m/px to approximately 0.06 m/px. We found that the Abydos site is as dark as… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2008.03180v1-abstract-full').style.display = 'inline'; document.getElementById('2008.03180v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2008.03180v1-abstract-full" style="display: none;"> We investigate Abydos, the final landing site of the Philae lander after its eventful landing from the Rosetta spacecraft on comet 67P/Churyumov-Gerasimenko on 12 November 2014. Over 1000 OSIRIS level 3B images were analysed, which cover the August 2014 to September 2016 timeframe, with spatial resolution ranging from 7.6 m/px to approximately 0.06 m/px. We found that the Abydos site is as dark as the global 67P nucleus and spectrally red, with an average albedo of 6.5% at 649 nm and a spectral slope value of about 17%/(100 nm) at 50$^\circ$ phase angle. Similar to the whole nucleus, the Abydos site also shows phase reddening but with lower coefficients than other regions of the comet which may imply a thinner cover of microscopically rough regolith compared to other areas. Seasonal variations, as already noticed for the whole nucleus, were also observed. We identified some potential morphological changes near the landing site implying a total mass loss of 4.7-7.0$\times$10$^5$ kg. Small spots ranging from 0.1 m$^2$ to 27 m$^2$ were observed close to Abydos before and after perihelion. Their estimated water ice abundance reaches 30-40% locally, indicating fresh exposures of volatiles. Their lifetime ranges from a few hours up to three months for two pre-perihelion spots. The Abydos surroundings showed low level of cometary activity compared to other regions of the nucleus. Only a few jets are reported originating nearby Abydos, including a bright outburst that lasted for about one hour. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2008.03180v1-abstract-full').style.display = 'none'; document.getElementById('2008.03180v1-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 August, 2020; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> August 2020. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1907.11081">arXiv:1907.11081</a> <span> [<a href="https://arxiv.org/pdf/1907.11081">pdf</a>, <a href="https://arxiv.org/format/1907.11081">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="Instrumentation and Methods for Astrophysics">astro-ph.IM</span> </div> </div> <p class="title is-5 mathjax"> AMBITION -- Comet Nucleus Cryogenic Sample Return (White paper for ESA's Voyage 2050 programme) </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Bockel%C3%A9e-Morvan%2C+D">D. Bockel茅e-Morvan</a>, <a href="/search/?searchtype=author&query=Filacchione%2C+G">G. Filacchione</a>, <a href="/search/?searchtype=author&query=Altwegg%2C+K">K. Altwegg</a>, <a href="/search/?searchtype=author&query=Bianchi%2C+E">E. Bianchi</a>, <a href="/search/?searchtype=author&query=Bizzarro%2C+M">M. Bizzarro</a>, <a href="/search/?searchtype=author&query=Blum%2C+J">J. Blum</a>, <a href="/search/?searchtype=author&query=Bonal%2C+L">L. Bonal</a>, <a href="/search/?searchtype=author&query=Capaccioni%2C+F">F. Capaccioni</a>, <a href="/search/?searchtype=author&query=Codella%2C+C">C. Codella</a>, <a href="/search/?searchtype=author&query=Choukroun%2C+M">M. Choukroun</a>, <a href="/search/?searchtype=author&query=Cottin%2C+H">H. Cottin</a>, <a href="/search/?searchtype=author&query=Davidsson%2C+B">B. Davidsson</a>, <a href="/search/?searchtype=author&query=De+Sanctis%2C+M+C">M. C. De Sanctis</a>, <a href="/search/?searchtype=author&query=Drozdovskaya%2C+M">M. Drozdovskaya</a>, <a href="/search/?searchtype=author&query=Engrand%2C+C">C. Engrand</a>, <a href="/search/?searchtype=author&query=Galand%2C+M">M. Galand</a>, <a href="/search/?searchtype=author&query=G%C3%BCttler%2C+C">C. G眉ttler</a>, <a href="/search/?searchtype=author&query=Henri%2C+P">P. Henri</a>, <a href="/search/?searchtype=author&query=Herique%2C+A">A. Herique</a>, <a href="/search/?searchtype=author&query=Ivanoski%2C+S">S. Ivanoski</a>, <a href="/search/?searchtype=author&query=Kokotanekova%2C+R">R. Kokotanekova</a>, <a href="/search/?searchtype=author&query=Levasseur-Regourd%2C+A+-">A. -C. Levasseur-Regourd</a>, <a href="/search/?searchtype=author&query=Miller%2C+K+E">K. E. Miller</a>, <a href="/search/?searchtype=author&query=Rotundi%2C+A">A. Rotundi</a>, <a href="/search/?searchtype=author&query=Sch%C3%B6nb%C3%A4chler%2C+M">M. Sch枚nb盲chler</a> , et al. (5 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1907.11081v1-abstract-short" style="display: inline;"> This white paper proposes that AMBITION, a Comet Nucleus Sample Return mission, be a cornerstone of ESA's Voyage 2050 programme. We summarise some of the most important questions still open in cometary science after the successes of the Rosetta mission, many of which require sample analysis using techniques that are only possible in laboratories on Earth. We then summarise measurements, instrument… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1907.11081v1-abstract-full').style.display = 'inline'; document.getElementById('1907.11081v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1907.11081v1-abstract-full" style="display: none;"> This white paper proposes that AMBITION, a Comet Nucleus Sample Return mission, be a cornerstone of ESA's Voyage 2050 programme. We summarise some of the most important questions still open in cometary science after the successes of the Rosetta mission, many of which require sample analysis using techniques that are only possible in laboratories on Earth. We then summarise measurements, instrumentation and mission scenarios that can address these questions, with a recommendation that ESA select an ambitious cryogenic sample return mission. Rendezvous missions to Main Belt comets and Centaurs are compelling cases for M-class missions, expanding our knowledge by exploring new classes of comets. AMBITION would engage a wide community, drawing expertise from a vast range of disciplines within planetary science and astrophysics. With AMBITION, Europe will continue its leadership in the exploration of the most primitive Solar System bodies. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1907.11081v1-abstract-full').style.display = 'none'; document.getElementById('1907.11081v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 25 July, 2019; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> July 2019. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">8 figures, 26 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/1905.03022">arXiv:1905.03022</a> <span> [<a href="https://arxiv.org/pdf/1905.03022">pdf</a>, <a href="https://arxiv.org/format/1905.03022">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/10.1051/0004-6361/201834869">10.1051/0004-6361/201834869 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Diurnal variation of dust and gas production in comet 67P/Churyumov-Gerasimenko at the inbound equinox as seen by OSIRIS and VIRTIS-M on board Rosetta </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Tubiana%2C+C">C. Tubiana</a>, <a href="/search/?searchtype=author&query=Rinaldi%2C+G">G. Rinaldi</a>, <a href="/search/?searchtype=author&query=G%C3%BCttler%2C+C">C. G眉ttler</a>, <a href="/search/?searchtype=author&query=Snodgrass%2C+C">C. Snodgrass</a>, <a href="/search/?searchtype=author&query=Shi%2C+X">X. Shi</a>, <a href="/search/?searchtype=author&query=Hu%2C+X">X. Hu</a>, <a href="/search/?searchtype=author&query=Marschall%2C+R">R. Marschall</a>, <a href="/search/?searchtype=author&query=Fulle%2C+M">M. Fulle</a>, <a href="/search/?searchtype=author&query=Bockel%C3%A9e-Morvan%2C+D">D. Bockel茅e-Morvan</a>, <a href="/search/?searchtype=author&query=Naletto%2C+G">G. Naletto</a>, <a href="/search/?searchtype=author&query=Capaccioni%2C+F">F. Capaccioni</a>, <a href="/search/?searchtype=author&query=Sierks%2C+H">H. Sierks</a>, <a href="/search/?searchtype=author&query=Arnold%2C+G">G. Arnold</a>, <a href="/search/?searchtype=author&query=Barucci%2C+M+A">M. A. Barucci</a>, <a href="/search/?searchtype=author&query=Bertaux%2C+J+-">J. -L. Bertaux</a>, <a href="/search/?searchtype=author&query=Bertini%2C+I">I. Bertini</a>, <a href="/search/?searchtype=author&query=Bodewits%2C+D">D. Bodewits</a>, <a href="/search/?searchtype=author&query=Capria%2C+M+T">M. T. Capria</a>, <a href="/search/?searchtype=author&query=Ciarniello%2C+M">M. Ciarniello</a>, <a href="/search/?searchtype=author&query=Cremonese%2C+G">G. Cremonese</a>, <a href="/search/?searchtype=author&query=Crovisier%2C+J">J. Crovisier</a>, <a href="/search/?searchtype=author&query=Da+Deppo%2C+V">V. Da Deppo</a>, <a href="/search/?searchtype=author&query=Debei%2C+S">S. Debei</a>, <a href="/search/?searchtype=author&query=De+Cecco%2C+M">M. De Cecco</a>, <a href="/search/?searchtype=author&query=Deller%2C+J">J. Deller</a> , et al. (31 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="1905.03022v1-abstract-short" style="display: inline;"> On 27 Apr 2015, when 67P/C-G was at 1.76 au from the Sun and moving towards perihelion, the OSIRIS and VIRTIS-M instruments on Rosetta observed the evolving dust and gas coma during a complete rotation of the comet. We aim to characterize the dust, H2O and CO2 gas spatial distribution in the inner coma. To do this we performed a quantitative analysis of the release of dust and gas and compared the… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1905.03022v1-abstract-full').style.display = 'inline'; document.getElementById('1905.03022v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1905.03022v1-abstract-full" style="display: none;"> On 27 Apr 2015, when 67P/C-G was at 1.76 au from the Sun and moving towards perihelion, the OSIRIS and VIRTIS-M instruments on Rosetta observed the evolving dust and gas coma during a complete rotation of the comet. We aim to characterize the dust, H2O and CO2 gas spatial distribution in the inner coma. To do this we performed a quantitative analysis of the release of dust and gas and compared the observed H2O production rate with the one calculated using a thermo-physical model. For this study we selected OSIRIS WAC images at 612 nm (dust) and VIRTIS-M image cubes at 612 nm, 2700 nm (H2O) and 4200 nm (CO2). We measured the average signal in a circular annulus, to study spatial variation around the comet, and in a sector of the annulus, to study temporal variation in the sunward direction with comet rotation, both at a fixed distance of 3.1 km from the comet centre. The spatial correlation between dust and water, both coming from the sun-lit side of the comet, shows that water is the main driver of dust activity in this time period. The spatial distribution of CO2 is not correlated with water and dust. There is no strong temporal correlation between the dust brightness and water production rate as the comet rotates. The dust brightness shows a peak at 0deg sub-solar longitude, which is not pronounced in the water production. At the same epoch, there is also a maximum in CO2 production. An excess of measured water production, with respect to the value calculated using a simple thermo-physical model, is observed when the head lobe and regions of the Southern hemisphere with strong seasonal variations are illuminated. A drastic decrease in dust production, when the water production (both measured and from the model) displays a maximum, happens when typical Northern consolidated regions are illuminated and the Southern hemisphere regions with strong seasonal variations are instead in shadow. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1905.03022v1-abstract-full').style.display = 'none'; document.getElementById('1905.03022v1-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 May, 2019; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> May 2019. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">15 pages, 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/1903.09017">arXiv:1903.09017</a> <span> [<a href="https://arxiv.org/pdf/1903.09017">pdf</a>, <a href="https://arxiv.org/format/1903.09017">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/10.1051/0004-6361/201834824">10.1051/0004-6361/201834824 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Surface evolution of the Anhur region on comet 67P from high-resolution OSIRIS images </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Fornasier%2C+S">S. Fornasier</a>, <a href="/search/?searchtype=author&query=Feller%2C+C">C. Feller</a>, <a href="/search/?searchtype=author&query=Hasselmann%2C+P+H">P. H. Hasselmann</a>, <a href="/search/?searchtype=author&query=Barucci%2C+M+A">M. A. Barucci</a>, <a href="/search/?searchtype=author&query=Sunshine%2C+J">J. Sunshine</a>, <a href="/search/?searchtype=author&query=Vincent%2C+J+-">J. -B. Vincent</a>, <a href="/search/?searchtype=author&query=Shi%2C+X">X. Shi</a>, <a href="/search/?searchtype=author&query=Sierks%2C+H">H. Sierks</a>, <a href="/search/?searchtype=author&query=Naletto%2C+G">G. Naletto</a>, <a href="/search/?searchtype=author&query=Lamy%2C+P+L">P. L. Lamy</a>, <a href="/search/?searchtype=author&query=Rodrigo%2C+R">R. Rodrigo</a>, <a href="/search/?searchtype=author&query=Koschny%2C+D">D. Koschny</a>, <a href="/search/?searchtype=author&query=Davidsson%2C+B">B. Davidsson</a>, <a href="/search/?searchtype=author&query=Bertaux%2C+J+-">J. -L. Bertaux</a>, <a href="/search/?searchtype=author&query=Bertini%2C+I">I. Bertini</a>, <a href="/search/?searchtype=author&query=Bodewits%2C+D">D. Bodewits</a>, <a href="/search/?searchtype=author&query=Cremonese%2C+G">G. Cremonese</a>, <a href="/search/?searchtype=author&query=Da+Deppo%2C+V">V. Da Deppo</a>, <a href="/search/?searchtype=author&query=Debei%2C+S">S. Debei</a>, <a href="/search/?searchtype=author&query=De+Cecco%2C+M">M. De Cecco</a>, <a href="/search/?searchtype=author&query=Deller%2C+J">J. Deller</a>, <a href="/search/?searchtype=author&query=Ferrari%2C+S">S. Ferrari</a>, <a href="/search/?searchtype=author&query=Fulle%2C+M">M. Fulle</a>, <a href="/search/?searchtype=author&query=Gutierrez%2C+P+J">P. J. Gutierrez</a>, <a href="/search/?searchtype=author&query=G%C3%BCttler%2C+C">C. G眉ttler</a> , et al. (12 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1903.09017v1-abstract-short" style="display: inline;"> The southern hemisphere of comet 67P/Churyumov-Gerasimenko (67P) became observable by the Rosetta mission in March 2015, a few months before cometary southern vernal equinox. The Anhur region in the southern part of the comet's larger lobe was found to be highly eroded, enriched in volatiles, and highly active. We analyze high-resolution images of the Anhur region pre- and post-perihelion acquired… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1903.09017v1-abstract-full').style.display = 'inline'; document.getElementById('1903.09017v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1903.09017v1-abstract-full" style="display: none;"> The southern hemisphere of comet 67P/Churyumov-Gerasimenko (67P) became observable by the Rosetta mission in March 2015, a few months before cometary southern vernal equinox. The Anhur region in the southern part of the comet's larger lobe was found to be highly eroded, enriched in volatiles, and highly active. We analyze high-resolution images of the Anhur region pre- and post-perihelion acquired by the OSIRIS imaging system on board the Rosetta mission. The Narrow Angle Camera is particularly useful for studying the evolution in Anhur in terms of morphological changes and color variations.}{Radiance factor images processed by the OSIRIS pipeline were coregistered, reprojected onto the 3D shape model of the comet, and corrected for the illumination conditions. We find a number of morphological changes in the Anhur region that are related to formation of new scarps; removal of dust coatings; localized resurfacing in some areas, including boulders displacements; and vanishing structures, which implies localized mass loss that we estimate to be higher than 50 million kg. The strongest changes took place in and nearby the Anhur canyon-like structure, where significant dust cover was removed, an entire structure vanished, and many boulders were rearranged. All such changes are potentially associated with one of the most intense outbursts registered by Rosetta during its observations, which occurred one day before perihelion passage. Moreover, in the niche at the foot of a new observed scarp, we also see evidence of water ice exposure that persisted for at least six months. The abundance of water ice, evaluated from a linear mixing model, is relatively high (> 20%). Our results confirm that the Anhur region is volatile-rich and probably is the area on 67P with the most pristine exposures near perihelion. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1903.09017v1-abstract-full').style.display = 'none'; document.getElementById('1903.09017v1-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 March, 2019; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> March 2019. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">19 pages, 16 figures; accepted for publication in Astronomy and Astrophysics for the Rosetta 2 special number</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> A&A 630, A13 (2019) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1902.10634">arXiv:1902.10634</a> <span> [<a href="https://arxiv.org/pdf/1902.10634">pdf</a>, <a href="https://arxiv.org/format/1902.10634">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/10.1051/0004-6361/201834751">10.1051/0004-6361/201834751 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Synthesis of the Morphological Description of Cometary Dust at Comet 67P </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=G%C3%BCttler%2C+C">C. G眉ttler</a>, <a href="/search/?searchtype=author&query=Mannel%2C+T">T. Mannel</a>, <a href="/search/?searchtype=author&query=Rotundi%2C+A">A. Rotundi</a>, <a href="/search/?searchtype=author&query=Merouane%2C+S">S. Merouane</a>, <a href="/search/?searchtype=author&query=Fulle%2C+M">M. Fulle</a>, <a href="/search/?searchtype=author&query=Bockel%C3%A9e-Morvan%2C+D">D. Bockel茅e-Morvan</a>, <a href="/search/?searchtype=author&query=Lasue%2C+J">J. Lasue</a>, <a href="/search/?searchtype=author&query=Levasseur-Regourd%2C+A+C">A. C. Levasseur-Regourd</a>, <a href="/search/?searchtype=author&query=Blum%2C+J">J. Blum</a>, <a href="/search/?searchtype=author&query=Naletto%2C+G">G. Naletto</a>, <a href="/search/?searchtype=author&query=Sierks%2C+H">H. Sierks</a>, <a href="/search/?searchtype=author&query=Hilchenbach%2C+M">M. Hilchenbach</a>, <a href="/search/?searchtype=author&query=Tubiana%2C+C">C. Tubiana</a>, <a href="/search/?searchtype=author&query=Capaccioni%2C+F">F. Capaccioni</a>, <a href="/search/?searchtype=author&query=Paquette%2C+J+A">J. A. Paquette</a>, <a href="/search/?searchtype=author&query=Flandes%2C+A">A. Flandes</a>, <a href="/search/?searchtype=author&query=Moreno%2C+F">F. Moreno</a>, <a href="/search/?searchtype=author&query=Agarwal%2C+J">J. Agarwal</a>, <a href="/search/?searchtype=author&query=Bodewits%2C+D">D. Bodewits</a>, <a href="/search/?searchtype=author&query=Bertini%2C+I">I. Bertini</a>, <a href="/search/?searchtype=author&query=Tozzi%2C+G+P">G. P. Tozzi</a>, <a href="/search/?searchtype=author&query=Hornung%2C+K">K. Hornung</a>, <a href="/search/?searchtype=author&query=Langevin%2C+Y">Y. Langevin</a>, <a href="/search/?searchtype=author&query=Kr%C3%BCger%2C+H">H. Kr眉ger</a>, <a href="/search/?searchtype=author&query=Longobardo%2C+A">A. Longobardo</a> , et al. (6 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="1902.10634v1-abstract-short" style="display: inline;"> Before Rosetta, the space missions Giotto and Stardust shaped our view on cometary dust, supported by plentiful data from Earth based observations and interplanetary dust particles collected in the Earth's atmosphere. The Rosetta mission at comet 67P/Churyumov-Gerasimenko was equipped with a multitude of instruments designed to study cometary dust. While an abundant amount of data was presented in… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1902.10634v1-abstract-full').style.display = 'inline'; document.getElementById('1902.10634v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1902.10634v1-abstract-full" style="display: none;"> Before Rosetta, the space missions Giotto and Stardust shaped our view on cometary dust, supported by plentiful data from Earth based observations and interplanetary dust particles collected in the Earth's atmosphere. The Rosetta mission at comet 67P/Churyumov-Gerasimenko was equipped with a multitude of instruments designed to study cometary dust. While an abundant amount of data was presented in several individual papers, many focused on a dedicated measurement or topic. Different instruments, methods, and data sources provide different measurement parameters and potentially introduce different biases. This can be an advantage if the complementary aspect of such a complex data set can be exploited. However, it also poses a challenge in the comparison of results in the first place. The aim of this work therefore is to summarise dust results from Rosetta and before. We establish a simple classification as a common framework for inter-comparison. This classification is based on a dust particle's structure, porosity, and strength as well as its size. Depending on the instrumentation, these are not direct measurement parameters but we chose them as they were the most reliable to derive our model. The proposed classification already proved helpful in the Rosetta dust community and we propose to take it into consideration also beyond. In this manner we hope to better identify synergies between different instruments and methods in the future. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1902.10634v1-abstract-full').style.display = 'none'; document.getElementById('1902.10634v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 27 February, 2019; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> February 2019. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">accepted 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 630, A24 (2019) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1812.09415">arXiv:1812.09415</a> <span> [<a href="https://arxiv.org/pdf/1812.09415">pdf</a>, <a href="https://arxiv.org/format/1812.09415">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/10.1051/0004-6361/201833807">10.1051/0004-6361/201833807 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> ROSETTA/OSIRIS observations of the 67P nucleus during the April 2016 flyby: high-resolution spectrophotometry </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Feller%2C+C">C. Feller</a>, <a href="/search/?searchtype=author&query=Fornasier%2C+S">S. Fornasier</a>, <a href="/search/?searchtype=author&query=Ferrari%2C+S">S. Ferrari</a>, <a href="/search/?searchtype=author&query=Hasselmann%2C+P+H">P. H. Hasselmann</a>, <a href="/search/?searchtype=author&query=Barucci%2C+A">A. Barucci</a>, <a href="/search/?searchtype=author&query=Massironi%2C+M">M. Massironi</a>, <a href="/search/?searchtype=author&query=Deshapriya%2C+J+D+P">J. D. P Deshapriya</a>, <a href="/search/?searchtype=author&query=Sierks%2C+H">H. Sierks</a>, <a href="/search/?searchtype=author&query=Naletto%2C+G">G. Naletto</a>, <a href="/search/?searchtype=author&query=Lamy%2C+P+L">P. L. Lamy</a>, <a href="/search/?searchtype=author&query=Rodrigo%2C+R">R. Rodrigo</a>, <a href="/search/?searchtype=author&query=Koschny%2C+D">D. Koschny</a>, <a href="/search/?searchtype=author&query=Davidsson%2C+B+J+R">B. J. R. Davidsson</a>, <a href="/search/?searchtype=author&query=Bertaux%2C+J+-">J. -L. Bertaux</a>, <a href="/search/?searchtype=author&query=Bertini%2C+I">I. Bertini</a>, <a href="/search/?searchtype=author&query=Bodewits%2C+D">D. Bodewits</a>, <a href="/search/?searchtype=author&query=Cremonese%2C+G">G. Cremonese</a>, <a href="/search/?searchtype=author&query=Da+Deppo%2C+V">V. Da Deppo</a>, <a href="/search/?searchtype=author&query=Debei%2C+S">S. Debei</a>, <a href="/search/?searchtype=author&query=De+Cecco%2C+M">M. De Cecco</a>, <a href="/search/?searchtype=author&query=Fulle%2C+M">M. Fulle</a>, <a href="/search/?searchtype=author&query=Guti%C3%A9rrez%2C+P+J">P. J. Guti茅rrez</a>, <a href="/search/?searchtype=author&query=G%C3%BCttler%2C+C">C. G眉ttler</a>, <a href="/search/?searchtype=author&query=Ip%2C+W+-">W. -H. Ip</a>, <a href="/search/?searchtype=author&query=Keller%2C+H+U">H. U. Keller</a> , et al. (13 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="1812.09415v1-abstract-short" style="display: inline;"> In April 2016, the Rosetta spacecraft performed a low-altitude low-phase-angle flyby over the Imhotep-Khepry transition of 67P/Churyumov-Gerasimenko's nucleus. The OSIRIS/Narrow-Angle-Camera (NAC) acquired 112 images with mainly 3 broadband filters in the visible at a resolution of up to 0.53 m/px and for phase angles between 0.095掳 and 62掳. Using those images, we have investigated the morphologic… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1812.09415v1-abstract-full').style.display = 'inline'; document.getElementById('1812.09415v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1812.09415v1-abstract-full" style="display: none;"> In April 2016, the Rosetta spacecraft performed a low-altitude low-phase-angle flyby over the Imhotep-Khepry transition of 67P/Churyumov-Gerasimenko's nucleus. The OSIRIS/Narrow-Angle-Camera (NAC) acquired 112 images with mainly 3 broadband filters in the visible at a resolution of up to 0.53 m/px and for phase angles between 0.095掳 and 62掳. Using those images, we have investigated the morphological and spectrophotometrical properties of this area. We assembled the images into coregistered color cubes. Using a 3D shape model, we produced the illumination conditions and georeference for each image. We projected the observations on a map to investigate its geomorphology. Observations were photometrically corrected using the Lommel-Seeliger disk law. Spectrophotometric analyses were performed on the coregistered color cubes. These data were used to estimate the local phase reddening. This region of the nucleus hosts numerous and varied types of terrains and features. We observe an association between a feature's nature, its reflectance, and its spectral slope. Fine material deposits exhibit an average reflectance and spectral slope, while terrains with diamictons, consolidated material, degraded outcrops, or features such as somber boulders, present a lower-than-average reflectance and higher-than-average spectral slope. Bright surfaces present here a spectral behavior consistent with terrains enriched in water-ice. We find a phase-reddening slope of 0.064{\pm}0.001{\%}/100nm/掳 at 2.7 au outbound, similarly to the one obtained at 2.3 au inbound during the February 2015 flyby. Identified as the source region of multiple jets and a host of water-ice material, the Imhotep-Khepry transition appeared in April 2016, close to the frost line, to further harbor several potential locations with exposed water-ice material among its numerous different morphological terrain units. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1812.09415v1-abstract-full').style.display = 'none'; document.getElementById('1812.09415v1-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 December, 2018; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> December 2018. </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">23 pages, 14 figures, 5 tables</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1809.10424">arXiv:1809.10424</a> <span> [<a href="https://arxiv.org/pdf/1809.10424">pdf</a>, <a href="https://arxiv.org/format/1809.10424">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/10.3847/1538-3881/aae526">10.3847/1538-3881/aae526 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Models of Rosetta/OSIRIS 67P dust coma phase function </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Moreno%2C+F">Fernando Moreno</a>, <a href="/search/?searchtype=author&query=Guirado%2C+D">Daniel Guirado</a>, <a href="/search/?searchtype=author&query=Mu%C3%B1oz%2C+O">Olga Mu帽oz</a>, <a href="/search/?searchtype=author&query=Bertini%2C+I">Ivano Bertini</a>, <a href="/search/?searchtype=author&query=Tubiana%2C+C">Cecilia Tubiana</a>, <a href="/search/?searchtype=author&query=Guttler%2C+C">Carsten Guttler</a>, <a href="/search/?searchtype=author&query=Fulle%2C+M">Marco Fulle</a>, <a href="/search/?searchtype=author&query=Rotundi%2C+A">Alessandra Rotundi</a>, <a href="/search/?searchtype=author&query=Della+Corte%2C+V">Vincenzo Della Corte</a>, <a href="/search/?searchtype=author&query=Ivanovski%2C+S">Stavro Ivanovski</a>, <a href="/search/?searchtype=author&query=Rinaldi%2C+G">Giovanna Rinaldi</a>, <a href="/search/?searchtype=author&query=Bockelee-Morvan%2C+D">Dominique Bockelee-Morvan</a>, <a href="/search/?searchtype=author&query=Zakharov%2C+V">Vladimir Zakharov</a>, <a href="/search/?searchtype=author&query=Agarwal%2C+J">Jessica Agarwal</a>, <a href="/search/?searchtype=author&query=Mottola%2C+S">Stefano Mottola</a>, <a href="/search/?searchtype=author&query=Toth%2C+I">Imre Toth</a>, <a href="/search/?searchtype=author&query=Frattin%2C+E">Elisa Frattin</a>, <a href="/search/?searchtype=author&query=Lara%2C+L">Luisa Lara</a>, <a href="/search/?searchtype=author&query=Gutierrez%2C+P">Pedro Gutierrez</a>, <a href="/search/?searchtype=author&query=Lin%2C+Z+Y">Zhong Yi Lin</a>, <a href="/search/?searchtype=author&query=Kolokolova%2C+L">Ludmilla Kolokolova</a>, <a href="/search/?searchtype=author&query=Sierks%2C+H">Holger Sierks</a>, <a href="/search/?searchtype=author&query=Naletto%2C+G">Giampiero Naletto</a>, <a href="/search/?searchtype=author&query=Lamy%2C+P">Philippe Lamy</a>, <a href="/search/?searchtype=author&query=Rodrigo%2C+R">Rafael Rodrigo</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="1809.10424v1-abstract-short" style="display: inline;"> The phase function of the dust coma of comet 67P has been determined from Rosetta/OSIRIS images \citep{Bertini17}. This function show a deep minimum at phase angles near 100$^\circ$, and a strong backscattering enhancement. These two properties cannot be reproduced by regular models of cometary dust, most of them based on wavelength-sized and randomly-oriented aggregate particles. We show, however… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1809.10424v1-abstract-full').style.display = 'inline'; document.getElementById('1809.10424v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1809.10424v1-abstract-full" style="display: none;"> The phase function of the dust coma of comet 67P has been determined from Rosetta/OSIRIS images \citep{Bertini17}. This function show a deep minimum at phase angles near 100$^\circ$, and a strong backscattering enhancement. These two properties cannot be reproduced by regular models of cometary dust, most of them based on wavelength-sized and randomly-oriented aggregate particles. We show, however, that an ensamble of oriented elongated particles of a wide variety of aspect ratios, with radii $r \gtrsim$10 $渭$m, and whose long axes are perpendicular to the direction of the solar radiation, are capable of reproducing the observed phase function. These particles must be absorbing, with an imaginary part of the refractive index of about 0.1 to match the expected geometric albedo, and with porosity in the 60-70\% range. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1809.10424v1-abstract-full').style.display = 'none'; document.getElementById('1809.10424v1-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 September, 2018; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> September 2018. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">Accepted by Astronomical Journal, September 26th, 2018. 21 pages, 5 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/1809.03997">arXiv:1809.03997</a> <span> [<a href="https://arxiv.org/pdf/1809.03997">pdf</a>, <a href="https://arxiv.org/format/1809.03997">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/10.1051/0004-6361/201833803">10.1051/0004-6361/201833803 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Linking surface morphology, composition, and activity on the nucleus of 67P/Churyumov-Gerasimenko </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Fornasier%2C+S">S. Fornasier</a>, <a href="/search/?searchtype=author&query=Hoang%2C+V+H">V. H. Hoang</a>, <a href="/search/?searchtype=author&query=Hasselmann%2C+P+H">P. H. Hasselmann</a>, <a href="/search/?searchtype=author&query=Feller%2C+C">C. Feller</a>, <a href="/search/?searchtype=author&query=Barucci%2C+M+A">M. A. Barucci</a>, <a href="/search/?searchtype=author&query=Deshapriya%2C+J+D+P">J. D. P. Deshapriya</a>, <a href="/search/?searchtype=author&query=Sierks%2C+H">H. Sierks</a>, <a href="/search/?searchtype=author&query=Naletto%2C+G">G. Naletto</a>, <a href="/search/?searchtype=author&query=Lamy%2C+P+L">P. L. Lamy</a>, <a href="/search/?searchtype=author&query=Rodrigo%2C+R">R. Rodrigo</a>, <a href="/search/?searchtype=author&query=Koschny%2C+D">D. Koschny</a>, <a href="/search/?searchtype=author&query=Davidsson%2C+B">B. Davidsson</a>, <a href="/search/?searchtype=author&query=Agarwal%2C+J">J. Agarwal</a>, <a href="/search/?searchtype=author&query=Barbieri%2C+C">C. Barbieri</a>, <a href="/search/?searchtype=author&query=Bertaux%2C+J+-">J. -L. Bertaux</a>, <a href="/search/?searchtype=author&query=Bertini%2C+I">I. Bertini</a>, <a href="/search/?searchtype=author&query=Bodewits%2C+D">D. Bodewits</a>, <a href="/search/?searchtype=author&query=Cremonese%2C+G">G. Cremonese</a>, <a href="/search/?searchtype=author&query=Da+Deppo%2C+V">V. Da Deppo</a>, <a href="/search/?searchtype=author&query=Debei%2C+S">S. Debei</a>, <a href="/search/?searchtype=author&query=De+Cecco%2C+M">M. De Cecco</a>, <a href="/search/?searchtype=author&query=Deller%2C+J">J. Deller</a>, <a href="/search/?searchtype=author&query=Ferrari%2C+S">S. Ferrari</a>, <a href="/search/?searchtype=author&query=Fulle%2C+M">M. Fulle</a>, <a href="/search/?searchtype=author&query=Gutierrez%2C+P+J">P. J. Gutierrez</a> , et al. (15 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="1809.03997v1-abstract-short" style="display: inline;"> The Rosetta space probe accompanied comet 67P/Churyumov-Gerasimenko for more than two years, obtaining an unprecedented amount of unique data of the comet nucleus and inner coma. This work focuses identifying the source regions of faint jets and outbursts and on studying the spectrophotometric properties of some outbursts. We use observations acquired with the OSIRIS/NAC camera during July-October… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1809.03997v1-abstract-full').style.display = 'inline'; document.getElementById('1809.03997v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1809.03997v1-abstract-full" style="display: none;"> The Rosetta space probe accompanied comet 67P/Churyumov-Gerasimenko for more than two years, obtaining an unprecedented amount of unique data of the comet nucleus and inner coma. This work focuses identifying the source regions of faint jets and outbursts and on studying the spectrophotometric properties of some outbursts. We use observations acquired with the OSIRIS/NAC camera during July-October 2015, that is, close to perihelion. More than 200 jets of different intensities were identified directly on the nucleus. Some of the more intense outbursts appear spectrally bluer than the comet dark terrain in the vivible-to-near-infrared region. We attribute this spectral behavior to icy grains mixed with the ejected dust. Some of the jets have an extremely short lifetime. They appear on the cometary surface during the color sequence observations, and vanish in less than some few minutes after reaching their peak. We also report a resolved dust plume observed in May 2016 at a resolution of 55 cm/pixel, which allowed us to estimate an optical depth of $\sim$0.65 and an ejected mass of $\sim$ 2200 kg. We present the results on the location, duration, and colors of active sources on the nucleus of 67P from the medium-resolution (i.e., 6-10 m/pixel) images acquired close to perihelion passage. The observed jets are mainly located close to boundaries between different morphological regions. Jets depart not only from cliffs, but also from smooth and dust-covered areas, from fractures, pits, or cavities that cast shadows and favor the recondensation of volatiles. This study shows that faint jets or outbursts continuously contribute to the cometary activity close to perihelion passage, and that these events are triggered by illumination conditions. Faint jets or outbursts are not associated with a particular terrain type or morphology. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1809.03997v1-abstract-full').style.display = 'none'; document.getElementById('1809.03997v1-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 September, 2018; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> September 2018. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">Accepted for publication on Astronomy and Astrophysics on 27 August 2018. 27 pages, 18 figures, 2 tables</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> A&A 630, A7 (2019) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1712.07508">arXiv:1712.07508</a> <span> [<a href="https://arxiv.org/pdf/1712.07508">pdf</a>, <a href="https://arxiv.org/format/1712.07508">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/10.1051/0004-6361/201732155">10.1051/0004-6361/201732155 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Tensile Strength of 67P/Churyumov-Gerasimenko Nucleus Material from Overhangs </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Attree%2C+N">N. Attree</a>, <a href="/search/?searchtype=author&query=Groussin%2C+O">O. Groussin</a>, <a href="/search/?searchtype=author&query=Jorda%2C+L">L. Jorda</a>, <a href="/search/?searchtype=author&query=N%C3%A9bouy%2C+D">D. N茅bouy</a>, <a href="/search/?searchtype=author&query=Thomas%2C+N">N. Thomas</a>, <a href="/search/?searchtype=author&query=Brouet%2C+Y">Y. Brouet</a>, <a href="/search/?searchtype=author&query=K%C3%BChrt%2C+E">E. K眉hrt</a>, <a href="/search/?searchtype=author&query=Preusker%2C+F">F. Preusker</a>, <a href="/search/?searchtype=author&query=Scholten%2C+F">F. Scholten</a>, <a href="/search/?searchtype=author&query=Knollenberg%2C+J">J. Knollenberg</a>, <a href="/search/?searchtype=author&query=Hartogh%2C+P">P. Hartogh</a>, <a href="/search/?searchtype=author&query=Sierks%2C+H">H. Sierks</a>, <a href="/search/?searchtype=author&query=Barbieri%2C+C">C. Barbieri</a>, <a href="/search/?searchtype=author&query=Lamy%2C+P">P. Lamy</a>, <a href="/search/?searchtype=author&query=Rodrigo%2C+R">R. Rodrigo</a>, <a href="/search/?searchtype=author&query=Koschny%2C+D">D. Koschny</a>, <a href="/search/?searchtype=author&query=Rickman%2C+H">H. Rickman</a>, <a href="/search/?searchtype=author&query=Keller%2C+H+U">H. U. Keller</a>, <a href="/search/?searchtype=author&query=A%27Hearn%2C+M+F">M. F. A'Hearn</a>, <a href="/search/?searchtype=author&query=Auger%2C+A+-">A. -T. Auger</a>, <a href="/search/?searchtype=author&query=Barucci%2C+M+A">M. A. Barucci</a>, <a href="/search/?searchtype=author&query=Bertaux%2C+J+-">J. -L. Bertaux</a>, <a href="/search/?searchtype=author&query=Bertini%2C+I">I. Bertini</a>, <a href="/search/?searchtype=author&query=Bodewits%2C+D">D. Bodewits</a>, <a href="/search/?searchtype=author&query=Boudreault%2C+S">S. Boudreault</a> , et al. (30 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="1712.07508v1-abstract-short" style="display: inline;"> We directly measure twenty overhanging cliffs on the surface of comet 67P/Churyumov-Gerasimenko extracted from the latest shape model and estimate the minimum tensile strengths needed to support them against collapse under the comet's gravity. We find extremely low strengths of around one Pa or less (one to five Pa, when scaled to a metre length). The presence of eroded material at the base of mos… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1712.07508v1-abstract-full').style.display = 'inline'; document.getElementById('1712.07508v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1712.07508v1-abstract-full" style="display: none;"> We directly measure twenty overhanging cliffs on the surface of comet 67P/Churyumov-Gerasimenko extracted from the latest shape model and estimate the minimum tensile strengths needed to support them against collapse under the comet's gravity. We find extremely low strengths of around one Pa or less (one to five Pa, when scaled to a metre length). The presence of eroded material at the base of most overhangs, as well as the observed collapse of two features and implied previous collapse of another, suggests that they are prone to failure and that true material strengths are close to these lower limits (although we only consider static stresses and not dynamic stress from, for example, cometary activity). Thus, a tensile strength of a few pascals is a good approximation for the tensile strength of 67P's nucleus material, which is in agreement with previous work. We find no particular trends in overhang properties with size, over the $\sim10-100$ m range studied here, or location on the nucleus. There are no obvious differences, in terms of strength, height or evidence of collapse, between the populations of overhangs on the two cometary lobes, suggesting that 67P is relatively homogenous in terms of tensile strength. Low material strengths are supportive of cometary formation as a primordial rubble pile or by collisional fragmentation of a small (tens of km) body. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1712.07508v1-abstract-full').style.display = 'none'; document.getElementById('1712.07508v1-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 December, 2017; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> December 2017. </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, 11 figures. Accepted for publication in Astronomy & Astrophysics</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> A&A 611, A33 (2018) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1710.10235">arXiv:1710.10235</a> <span> [<a href="https://arxiv.org/pdf/1710.10235">pdf</a>, <a href="https://arxiv.org/format/1710.10235">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/10.1093/mnras/stx2386">10.1093/mnras/stx2386 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Evidence of sub-surface energy storage in comet 67P from the outburst of 2016 July 3 </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Agarwal%2C+J">J. Agarwal</a>, <a href="/search/?searchtype=author&query=Della+Corte%2C+V">V. Della Corte</a>, <a href="/search/?searchtype=author&query=Feldman%2C+P+D">P. D. Feldman</a>, <a href="/search/?searchtype=author&query=Geiger%2C+B">B. Geiger</a>, <a href="/search/?searchtype=author&query=Merouane%2C+S">S. Merouane</a>, <a href="/search/?searchtype=author&query=Bertini%2C+I">I. Bertini</a>, <a href="/search/?searchtype=author&query=Bodewits%2C+D">D. Bodewits</a>, <a href="/search/?searchtype=author&query=Fornasier%2C+S">S. Fornasier</a>, <a href="/search/?searchtype=author&query=Gruen%2C+E">E. Gruen</a>, <a href="/search/?searchtype=author&query=Hasselmann%2C+P">P. Hasselmann</a>, <a href="/search/?searchtype=author&query=Hilchenbach%2C+M">M. Hilchenbach</a>, <a href="/search/?searchtype=author&query=Hoefner%2C+S">S. Hoefner</a>, <a href="/search/?searchtype=author&query=Ivanovski%2C+S">S. Ivanovski</a>, <a href="/search/?searchtype=author&query=Kolokolova%2C+L">L. Kolokolova</a>, <a href="/search/?searchtype=author&query=Pajola%2C+M">M. Pajola</a>, <a href="/search/?searchtype=author&query=Rotundi%2C+A">A. Rotundi</a>, <a href="/search/?searchtype=author&query=Sierks%2C+H">H. Sierks</a>, <a href="/search/?searchtype=author&query=Steffl%2C+A+J">A. J. Steffl</a>, <a href="/search/?searchtype=author&query=Thomas%2C+N">N. Thomas</a>, <a href="/search/?searchtype=author&query=A%27Hearn%2C+M+F">M. F. A'Hearn</a>, <a href="/search/?searchtype=author&query=Barbieri%2C+C">C. Barbieri</a>, <a href="/search/?searchtype=author&query=Barucci%2C+M+A">M. A. Barucci</a>, <a href="/search/?searchtype=author&query=Bertaux%2C+J+-">J. -L. Bertaux</a>, <a href="/search/?searchtype=author&query=Boudreault%2C+S">S. Boudreault</a>, <a href="/search/?searchtype=author&query=Cremonese%2C+G">G. Cremonese</a> , et al. (45 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="1710.10235v1-abstract-short" style="display: inline;"> On 3 July 2016, several instruments on board ESA's Rosetta spacecraft detected signs of an outburst event on comet 67P, at a heliocentric distance of 3.32 AU from the sun, outbound from perihelion. We here report on the inferred properties of the ejected dust and the surface change at the site of the outburst. The activity coincided with the local sunrise and continued over a time interval of 14 -… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1710.10235v1-abstract-full').style.display = 'inline'; document.getElementById('1710.10235v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1710.10235v1-abstract-full" style="display: none;"> On 3 July 2016, several instruments on board ESA's Rosetta spacecraft detected signs of an outburst event on comet 67P, at a heliocentric distance of 3.32 AU from the sun, outbound from perihelion. We here report on the inferred properties of the ejected dust and the surface change at the site of the outburst. The activity coincided with the local sunrise and continued over a time interval of 14 - 68 minutes. It left a 10m-sized icy patch on the surface. The ejected material comprised refractory grains of several hundred microns in size, and sub-micron-sized water ice grains. The high dust mass production rate is incompatible with the free sublimation of crystalline water ice under solar illumination as the only acceleration process. Additional energy stored near the surface must have increased the gas density. We suggest a pressurized sub-surface gas reservoir, or the crystallization of amorphous water ice as possible causes. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1710.10235v1-abstract-full').style.display = 'none'; document.getElementById('1710.10235v1-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 October, 2017; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> October 2017. </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, 19 figures, 5 tables</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> MNRAS 469, S606-S625, 2017 </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1710.01019">arXiv:1710.01019</a> <span> [<a href="https://arxiv.org/pdf/1710.01019">pdf</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"> Centrifugal Experiments with Simulated Regolith:Effects of Gravity, Size Distribution, and Particle Shape on Porosity </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Omura%2C+T">Tomomi Omura</a>, <a href="/search/?searchtype=author&query=Kiuchi%2C+m">masato Kiuchi</a>, <a href="/search/?searchtype=author&query=G%C3%BCttler%2C+C">Carsten G眉ttler</a>, <a href="/search/?searchtype=author&query=Nakamura%2C+A+M">Akiko M. Nakamura</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="1710.01019v1-abstract-short" style="display: inline;"> Porosity is a key characteristic of the regolith on the surface of small bodies. The porosity of the regolith on the surface of asteroids is changed by applied pressure, and the relationship between pressure and porosity depends on the particle properties of the regolith. We performed compression measurements on samples of different materials, particle size distributions, and shapes to examine the… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1710.01019v1-abstract-full').style.display = 'inline'; document.getElementById('1710.01019v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1710.01019v1-abstract-full" style="display: none;"> Porosity is a key characteristic of the regolith on the surface of small bodies. The porosity of the regolith on the surface of asteroids is changed by applied pressure, and the relationship between pressure and porosity depends on the particle properties of the regolith. We performed compression measurements on samples of different materials, particle size distributions, and shapes to examine the relationship between particle size and pressure required for compression. We used a centrifuge and a compression testing machine for the experiments. The applied pressure for the centrifuge and the compression testing machine experiments ranged from 10^2 to 5x10^3 Pa and from 10^4 to 5x10^6 Pa, respectively. The initial porosity before compression was generally higher for samples with smaller particles and narrower particle size distributions. A sample compressed more easily when it consisted of smaller particles, probably due to smaller frictional forces between particles. We estimated the porosity of granular asteroids based on the results of our experiments. The estimated porosity at the center of a homogeneous asteroid with a radius of 50 km is 0.43. This porosity is typical of the porosity of asteroids of similar size. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1710.01019v1-abstract-full').style.display = 'none'; document.getElementById('1710.01019v1-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 October, 2017; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> October 2017. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Trans. JSASS Aerosp. Tech. Jpn., 14 (2016), Pk_17-Pk_21 </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1707.06812">arXiv:1707.06812</a> <span> [<a href="https://arxiv.org/pdf/1707.06812">pdf</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/10.1093/mnras/stx1726">10.1093/mnras/stx1726 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Seasonal Mass Transfer on the Nucleus of Comet 67P/Chuyumov-Gerasimenko </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Keller%2C+H+U">H. U. Keller</a>, <a href="/search/?searchtype=author&query=Mottola%2C+S">S. Mottola</a>, <a href="/search/?searchtype=author&query=Hviid%2C+S+F">S. F. Hviid</a>, <a href="/search/?searchtype=author&query=Agarwal%2C+J">J. Agarwal</a>, <a href="/search/?searchtype=author&query=K%C3%BChrt%2C+E">E. K眉hrt</a>, <a href="/search/?searchtype=author&query=Skorov%2C+Y">Y. Skorov</a>, <a href="/search/?searchtype=author&query=Otto%2C+K">K. Otto</a>, <a href="/search/?searchtype=author&query=Vincent%2C+J+-">J. -B. Vincent</a>, <a href="/search/?searchtype=author&query=Oklay%2C+N">N. Oklay</a>, <a href="/search/?searchtype=author&query=Schr%C3%B6der%2C+S+E">S. E. Schr枚der</a>, <a href="/search/?searchtype=author&query=Davidsson%2C+B">B. Davidsson</a>, <a href="/search/?searchtype=author&query=Pajola%2C+M">M. Pajola</a>, <a href="/search/?searchtype=author&query=Shi%2C+X">X. Shi</a>, <a href="/search/?searchtype=author&query=Bodewits%2C+D">D. Bodewits</a>, <a href="/search/?searchtype=author&query=Toth%2C+I">I. Toth</a>, <a href="/search/?searchtype=author&query=Preusker%2C+F">F. Preusker</a>, <a href="/search/?searchtype=author&query=Scholten%2C+F">F. Scholten</a>, <a href="/search/?searchtype=author&query=Sierks%2C+H">H. Sierks</a>, <a href="/search/?searchtype=author&query=Barbieri%2C+C">C. Barbieri</a>, <a href="/search/?searchtype=author&query=Lamy%2C+P">P. Lamy</a>, <a href="/search/?searchtype=author&query=Rodrigo%2C+R">R. Rodrigo</a>, <a href="/search/?searchtype=author&query=Koschny%2C+D">D. Koschny</a>, <a href="/search/?searchtype=author&query=Rickman%2C+H">H. Rickman</a>, <a href="/search/?searchtype=author&query=A%27Hearn%2C+M+F">M. F. A'Hearn</a>, <a href="/search/?searchtype=author&query=Barucci%2C+M+A">M. A. Barucci</a> , et al. (25 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="1707.06812v1-abstract-short" style="display: inline;"> We collect observational evidence that supports the scheme of mass transfer on the nucleus of comet 67P/Churyumov-Gerasimenko. The obliquity of the rotation axis of 67P causes strong seasonal variations. During perihelion the southern hemisphere is four times more active than the north. Northern territories are widely covered by granular material that indicates back fall originating from the activ… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1707.06812v1-abstract-full').style.display = 'inline'; document.getElementById('1707.06812v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1707.06812v1-abstract-full" style="display: none;"> We collect observational evidence that supports the scheme of mass transfer on the nucleus of comet 67P/Churyumov-Gerasimenko. The obliquity of the rotation axis of 67P causes strong seasonal variations. During perihelion the southern hemisphere is four times more active than the north. Northern territories are widely covered by granular material that indicates back fall originating from the active south. Decimetre sized chunks contain water ice and their trajectories are influenced by an anti-solar force instigated by sublimation. OSIRIS observations suggest that up to 20 % of the particles directly return to the nucleus surface taking several hours of travel time. The back fall covered northern areas are active if illuminated but produce mainly water vapour. The decimetre chunks from the nucleus surface are too small to contain more volatile compounds such as CO 2 or CO. This causes a north-south dichotomy of the composition measurements in the coma. Active particles are trapped in the gravitational minimum of Hapi during northern winter. They are "shock frozen" and only reactivated when the comet approaches the sun after its aphelion passage. The insolation of the big cavity is enhanced by self-heating, i. e. reflection and IR radiation from the walls. This, together with the pristinity of the active back fall, explains the early observed activity of the Hapi region. Sobek may be a role model for the consolidated bottom of Hapi. Mass transfer in the case of 67P strongly influences the evolution of the nucleus and the interpretation of coma measurements. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1707.06812v1-abstract-full').style.display = 'none'; document.getElementById('1707.06812v1-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, 2017; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> July 2017. </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">17 pages, 20 figures</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Monthly Notices of the Royal Astronomical Society stx1726, 13 July 2017 </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1707.02945">arXiv:1707.02945</a> <span> [<a href="https://arxiv.org/pdf/1707.02945">pdf</a>, <a href="https://arxiv.org/format/1707.02945">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/10.1093/mnras/stx1275">10.1093/mnras/stx1275 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> The highly active Anhur-Bes regions in the 67P/Churyumov - Gerasimenko comet: results from OSIRIS/ROSETTA observations </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Fornasier%2C+S">S. Fornasier</a>, <a href="/search/?searchtype=author&query=Feller%2C+C">C. Feller</a>, <a href="/search/?searchtype=author&query=Lee%2C+J+C">J. C. Lee</a>, <a href="/search/?searchtype=author&query=Ferrari%2C+S">S. Ferrari</a>, <a href="/search/?searchtype=author&query=Massironi%2C+M">M. Massironi</a>, <a href="/search/?searchtype=author&query=Hasselmann%2C+P+H">P. H. Hasselmann</a>, <a href="/search/?searchtype=author&query=Deshapriya%2C+J+D+P">J. D. P Deshapriya</a>, <a href="/search/?searchtype=author&query=Barucci%2C+M+A">M. A. Barucci</a>, <a href="/search/?searchtype=author&query=El-Maarry%2C+M+R">M. R. El-Maarry</a>, <a href="/search/?searchtype=author&query=Giacomini%2C+L">L. Giacomini</a>, <a href="/search/?searchtype=author&query=Mottola%2C+S">S. Mottola</a>, <a href="/search/?searchtype=author&query=Keller%2C+H+U">H. U. Keller</a>, <a href="/search/?searchtype=author&query=Ip%2C+W+H">W. H. Ip</a>, <a href="/search/?searchtype=author&query=Lin%2C+Z+Y">Z. Y. Lin</a>, <a href="/search/?searchtype=author&query=Sierks%2C+H">H. Sierks</a>, <a href="/search/?searchtype=author&query=Barbieri%2C+C">C. Barbieri</a>, <a href="/search/?searchtype=author&query=Lamy%2C+P+L">P. L. Lamy</a>, <a href="/search/?searchtype=author&query=Rodrigo%2C+R">R. Rodrigo</a>, <a href="/search/?searchtype=author&query=Koschny%2C+D">D. Koschny</a>, <a href="/search/?searchtype=author&query=Rickman%2C+H">H. Rickman</a>, <a href="/search/?searchtype=author&query=Agarwal%2C+J">J. Agarwal</a>, <a href="/search/?searchtype=author&query=A%27Hearn%2C+M">M. A'Hearn</a>, <a href="/search/?searchtype=author&query=Bertaux%2C+J+-">J. -L. Bertaux</a>, <a href="/search/?searchtype=author&query=Bertini%2C+I">I. Bertini</a>, <a href="/search/?searchtype=author&query=Cremonese%2C+G">G. Cremonese</a> , et al. (29 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="1707.02945v1-abstract-short" style="display: inline;"> The Southern hemisphere of the 67P/Churyumov-Gerasimenko comet has become visible from Rosetta only since March 2015. It was illuminated during the perihelion passage and therefore it contains the regions that experienced the strongest heating and erosion rate, thus exposing the subsurface most pristine material. In this work we investigate, thanks to the OSIRIS images, the geomorphology, the spec… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1707.02945v1-abstract-full').style.display = 'inline'; document.getElementById('1707.02945v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1707.02945v1-abstract-full" style="display: none;"> The Southern hemisphere of the 67P/Churyumov-Gerasimenko comet has become visible from Rosetta only since March 2015. It was illuminated during the perihelion passage and therefore it contains the regions that experienced the strongest heating and erosion rate, thus exposing the subsurface most pristine material. In this work we investigate, thanks to the OSIRIS images, the geomorphology, the spectrophotometry and some transient events of two Southern hemisphere regions: Anhur and part of Bes. Bes is dominated by outcropping consolidated terrain covered with fine particle deposits, while Anhur appears strongly eroded with elongated canyon-like structures, scarp retreats, different kinds of deposits, and degraded sequences of strata indicating a pervasive layering. We discovered a new 140 m long and 10 m high scarp formed in the Anhur/Bes boundary during/after the perihelion passage, close to the area where exposed CO$_2$ and H$_2$O ices were previously detected. Several jets have been observed originating from these regions, including the strong perihelion outburst, an active pit, and a faint optically thick dust plume. We identify several areas with a relatively bluer slope (i.e. a lower spectral slope value) than their surroundings, indicating a surface composition enriched with some water ice. These spectrally bluer areas are observed especially in talus and gravitational accumulation deposits where freshly exposed material had fallen from nearby scarps and cliffs. The investigated regions become spectrally redder beyond 2 au outbound when the dust mantle became thicker, masking the underlying ice-rich layers. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1707.02945v1-abstract-full').style.display = 'none'; document.getElementById('1707.02945v1-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 July, 2017; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> July 2017. </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, 15 figures, published online on 24 May 2017 on Mon. Not. R. Astron. Soc. stx1275, https://doi.org/10.1093/mnras/stx1275</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1707.00734">arXiv:1707.00734</a> <span> [<a href="https://arxiv.org/pdf/1707.00734">pdf</a>, <a href="https://arxiv.org/format/1707.00734">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/10.1093/mnras/stx1691">10.1093/mnras/stx1691 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Constraints on cometary surface evolution derived from a statistical analysis of 67P's topography </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Vincent%2C+J+-">J. -B. Vincent</a>, <a href="/search/?searchtype=author&query=Hviid%2C+S+F">S. F. Hviid</a>, <a href="/search/?searchtype=author&query=Mottola%2C+S">S. Mottola</a>, <a href="/search/?searchtype=author&query=Kuehrt%2C+E">E. Kuehrt</a>, <a href="/search/?searchtype=author&query=Preusker%2C+F">F. Preusker</a>, <a href="/search/?searchtype=author&query=Scholten%2C+F">F. Scholten</a>, <a href="/search/?searchtype=author&query=Keller%2C+H+U">H. U. Keller</a>, <a href="/search/?searchtype=author&query=Oklay%2C+N">N. Oklay</a>, <a href="/search/?searchtype=author&query=de+Niem%2C+D">D. de Niem</a>, <a href="/search/?searchtype=author&query=Davidsson%2C+B">B. Davidsson</a>, <a href="/search/?searchtype=author&query=Fulle%2C+M">M. Fulle</a>, <a href="/search/?searchtype=author&query=Pajola%2C+M">M. Pajola</a>, <a href="/search/?searchtype=author&query=Hofmann%2C+M">M. Hofmann</a>, <a href="/search/?searchtype=author&query=Hu%2C+X">X. Hu</a>, <a href="/search/?searchtype=author&query=Rickman%2C+H">H. Rickman</a>, <a href="/search/?searchtype=author&query=Lin%2C+Z+-">Z. -Y. Lin</a>, <a href="/search/?searchtype=author&query=Feller%2C+C">C. Feller</a>, <a href="/search/?searchtype=author&query=Gicquel%2C+A">A. Gicquel</a>, <a href="/search/?searchtype=author&query=Boudreault%2C+S">S. Boudreault</a>, <a href="/search/?searchtype=author&query=Sierks%2C+H">H. Sierks</a>, <a href="/search/?searchtype=author&query=Barbieri%2C+C">C. Barbieri</a>, <a href="/search/?searchtype=author&query=Lamy%2C+P+L">P. L. Lamy</a>, <a href="/search/?searchtype=author&query=Rodrigo%2C+R">R. Rodrigo</a>, <a href="/search/?searchtype=author&query=Koschny%2C+D">D. Koschny</a>, <a href="/search/?searchtype=author&query=A%27Hearn%2C+M+F">M. F. A'Hearn</a> , et al. (29 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="1707.00734v2-abstract-short" style="display: inline;"> We present a statistical analysis of the distribution of large scale topographic features on comet 67P/Churyumov-Gerasimenko. We observe that the cumulative cliff height distribution across the surface follows a power law with a slope equal to -1.69 +- 0.02. When this distribution is studied independently for each region, we find a good correlation between the slope of the power law and the orbita… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1707.00734v2-abstract-full').style.display = 'inline'; document.getElementById('1707.00734v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1707.00734v2-abstract-full" style="display: none;"> We present a statistical analysis of the distribution of large scale topographic features on comet 67P/Churyumov-Gerasimenko. We observe that the cumulative cliff height distribution across the surface follows a power law with a slope equal to -1.69 +- 0.02. When this distribution is studied independently for each region, we find a good correlation between the slope of the power law and the orbital erosion rate of the surface. For instance, the northern hemisphere topography is dominated by structures on the 100~m scale while the southern hemisphere topography, illuminated at perihelion, is dominated by 10~m scale terrain features. Our study suggest that the current size of a cliff is controlled not only by material cohesion but by the dominant erosional process in each region. This observation can be generalized to other comets, where we argue that primitive nuclei are characterized by the presence of large cliffs with a cumulative height power index equal to or above -1.5, while older, eroded cometary surfaces have a power index equal to or below -2.3. In effect, our model shows that a measure of the topography provides a quantitative assessment of a comet's erosional history, i.e. its evolutionary age. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1707.00734v2-abstract-full').style.display = 'none'; document.getElementById('1707.00734v2-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> 24 July, 2017; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 3 July, 2017; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> July 2017. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1706.02729">arXiv:1706.02729</a> <span> [<a href="https://arxiv.org/pdf/1706.02729">pdf</a>, <a href="https://arxiv.org/ps/1706.02729">ps</a>, <a href="https://arxiv.org/format/1706.02729">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/10.1093/mnras/stx1441">10.1093/mnras/stx1441 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Modeling of the outburst on July 29th, 2015 observed with OSIRIS cameras in the southern hemisphere of comet 67P/Churyumov-Gerasimenko </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Gicquel%2C+A">A. Gicquel</a>, <a href="/search/?searchtype=author&query=Rose%2C+M">M. Rose</a>, <a href="/search/?searchtype=author&query=Vincent%2C+J+-">J. -B. Vincent</a>, <a href="/search/?searchtype=author&query=Davidsson%2C+B">B. Davidsson</a>, <a href="/search/?searchtype=author&query=Bodewits%2C+D">D. Bodewits</a>, <a href="/search/?searchtype=author&query=Hearn%2C+M+F+A">M. F. A Hearn</a>, <a href="/search/?searchtype=author&query=Agarwal%2C+J">J. Agarwal</a>, <a href="/search/?searchtype=author&query=Fougere%2C+N">N. Fougere</a>, <a href="/search/?searchtype=author&query=Sierks%2C+H">H. Sierks</a>, <a href="/search/?searchtype=author&query=Bertini%2C+I">I. Bertini</a>, <a href="/search/?searchtype=author&query=Lin%2C+Z+-">Z. -Y. Lin</a>, <a href="/search/?searchtype=author&query=Barbieri%2C+C">C. Barbieri</a>, <a href="/search/?searchtype=author&query=Lamy%2C+P+L">P. L. Lamy</a>, <a href="/search/?searchtype=author&query=Rodrigo%2C+R">R. Rodrigo</a>, <a href="/search/?searchtype=author&query=Koschny%2C+D">D. Koschny</a>, <a href="/search/?searchtype=author&query=Rickman%2C+H">H. Rickman</a>, <a href="/search/?searchtype=author&query=Keller%2C+H+U">H. U. Keller</a>, <a href="/search/?searchtype=author&query=Barucci%2C+M+A">M. A. Barucci</a>, <a href="/search/?searchtype=author&query=Bertaux%2C+J+-">J. -L. Bertaux</a>, <a href="/search/?searchtype=author&query=Besse%2C+S">S. Besse</a>, <a href="/search/?searchtype=author&query=Boudreault%2C+S">S. Boudreault</a>, <a href="/search/?searchtype=author&query=Cremonese%2C+G">G. Cremonese</a>, <a href="/search/?searchtype=author&query=Da+Deppo%2C+V">V. Da Deppo</a>, <a href="/search/?searchtype=author&query=Debei%2C+S">S. Debei</a>, <a href="/search/?searchtype=author&query=Deller%2C+J">J. Deller</a> , et al. (38 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="1706.02729v1-abstract-short" style="display: inline;"> Images of the nucleus and the coma (gas and dust) of comet 67P/Churyumov- Gerasimenko have been acquired by the OSIRIS (Optical, Spectroscopic, and Infrared Remote Imaging System) cameras since March 2014 using both the Wide Angle Camera (WAC) and the Narrow Angle Camera (NAC). We use images from the NAC camera to study a bright outburst observed in the southern hemisphere on July 29, 2015. The hi… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1706.02729v1-abstract-full').style.display = 'inline'; document.getElementById('1706.02729v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1706.02729v1-abstract-full" style="display: none;"> Images of the nucleus and the coma (gas and dust) of comet 67P/Churyumov- Gerasimenko have been acquired by the OSIRIS (Optical, Spectroscopic, and Infrared Remote Imaging System) cameras since March 2014 using both the Wide Angle Camera (WAC) and the Narrow Angle Camera (NAC). We use images from the NAC camera to study a bright outburst observed in the southern hemisphere on July 29, 2015. The high spatial resolution of the NAC is needed to localize the source point of the outburst on the surface of the nucleus. The heliocentric distance is 1.25 au and the spacecraft-comet distance is 186 km. Aiming to better understand the physics that led to the outgassing, we used the Direct Simulation Monte Carlo (DSMC) method to study the gas flow close to the nucleus and the dust trajectories. The goal is to understand the mechanisms producing the outburst. We reproduce the opening angle of the outburst in the model and constrain the outgassing ratio between the outburst source and the local region. The outburst is in fact a combination of both gas and dust, in which the active surface is approximately 10 times more active than the average rate found in the surrounding areas. We need a number of dust particles 7.83 $\times$ 10$^{11}$ - 6.90 $\times$ 10$^{15}$ (radius 1.97 - 185 渭m), which corresponds to a mass of dust 220 - 21 $\times$ 10$^{3}$kg. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1706.02729v1-abstract-full').style.display = 'none'; document.getElementById('1706.02729v1-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 June, 2017; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> June 2017. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">8 pages, 9 figures</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Report number:</span> MN-17-1040-MJ.R1 </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1705.03740">arXiv:1705.03740</a> <span> [<a href="https://arxiv.org/pdf/1705.03740">pdf</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/10.1016/j.pss.2017.04.018">10.1016/j.pss.2017.04.018 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Distance determination method of dust particles using Rosetta OSIRIS NAC and WAC data </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Drolshagen%2C+E">E. Drolshagen</a>, <a href="/search/?searchtype=author&query=Ott%2C+T">T. Ott</a>, <a href="/search/?searchtype=author&query=Koschny%2C+D">D. Koschny</a>, <a href="/search/?searchtype=author&query=G%C3%BCttler%2C+C">C. G眉ttler</a>, <a href="/search/?searchtype=author&query=Tubiana%2C+C">C. Tubiana</a>, <a href="/search/?searchtype=author&query=Agarwal%2C+J">J. Agarwal</a>, <a href="/search/?searchtype=author&query=Sierks%2C+H">H. Sierks</a>, <a href="/search/?searchtype=author&query=Barbieri%2C+C">C. Barbieri</a>, <a href="/search/?searchtype=author&query=Lamy%2C+P+I">P. I. Lamy</a>, <a href="/search/?searchtype=author&query=Rodrigo%2C+R">R. Rodrigo</a>, <a href="/search/?searchtype=author&query=Rickman%2C+H">H. Rickman</a>, <a href="/search/?searchtype=author&query=A%27Hearn%2C+M+F">M. F. A'Hearn</a>, <a href="/search/?searchtype=author&query=Barucci%2C+M+A">M. A. Barucci</a>, <a href="/search/?searchtype=author&query=Bertaux%2C+J+-">J. -L. Bertaux</a>, <a href="/search/?searchtype=author&query=Bertini%2C+I">I. Bertini</a>, <a href="/search/?searchtype=author&query=Cremonese%2C+G">G. Cremonese</a>, <a href="/search/?searchtype=author&query=Da+Deppo%2C+V">V. Da Deppo</a>, <a href="/search/?searchtype=author&query=Davidsson%2C+B">B. Davidsson</a>, <a href="/search/?searchtype=author&query=Debei%2C+S">S. Debei</a>, <a href="/search/?searchtype=author&query=De+Cecco%2C+M">M. De Cecco</a>, <a href="/search/?searchtype=author&query=Deller%2C+J">J. Deller</a>, <a href="/search/?searchtype=author&query=Feller%2C+C">C. Feller</a>, <a href="/search/?searchtype=author&query=Fornasier%2C+S">S. Fornasier</a>, <a href="/search/?searchtype=author&query=Fulle%2C+M">M. Fulle</a>, <a href="/search/?searchtype=author&query=Gicquel%2C+A">A. Gicquel</a> , et al. (20 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="1705.03740v1-abstract-short" style="display: inline;"> The ESA Rosetta spacecraft has been tracking its target, the Jupiter-family comet 67P/Churyumov-Gerasimenko, in close vicinity for over two years. It hosts the OSIRIS instruments: the Optical, Spectroscopic, and Infrared Remote Imaging System composed of two cameras, see e.g. Keller et al. (2007). In some imaging sequences dedicated to observe dust particles in the comet's coma, the two cameras to… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1705.03740v1-abstract-full').style.display = 'inline'; document.getElementById('1705.03740v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1705.03740v1-abstract-full" style="display: none;"> The ESA Rosetta spacecraft has been tracking its target, the Jupiter-family comet 67P/Churyumov-Gerasimenko, in close vicinity for over two years. It hosts the OSIRIS instruments: the Optical, Spectroscopic, and Infrared Remote Imaging System composed of two cameras, see e.g. Keller et al. (2007). In some imaging sequences dedicated to observe dust particles in the comet's coma, the two cameras took images at the same time. The aim of this work is to use these simultaneous double camera observations to calculate the dust particles' distance to the spacecraft. As the two cameras are mounted on the spacecraft with an offset of 70 cm, the distance of particles observed by both cameras can be determined by a shift of the particles' apparent trails on the images. This paper presents first results of the ongoing work, introducing the distance determination method for the OSIRIS instrument and the analysis of an example particle. We note that this method works for particles in the range of about 500 m - 6000 m from the spacecraft. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1705.03740v1-abstract-full').style.display = 'none'; document.getElementById('1705.03740v1-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, 2017; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> May 2017. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1611.00012">arXiv:1611.00012</a> <span> [<a href="https://arxiv.org/pdf/1611.00012">pdf</a>, <a href="https://arxiv.org/format/1611.00012">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/10.1093/mnras/stw2511">10.1093/mnras/stw2511 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Decimetre-scaled spectrophotometric properties of the nucleus of comet 67P/Churyumov-Gerasimenko from OSIRIS observations </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Feller%2C+C">C. Feller</a>, <a href="/search/?searchtype=author&query=Fornasier%2C+S">S. Fornasier</a>, <a href="/search/?searchtype=author&query=Hasselmann%2C+P+H">P. H. Hasselmann</a>, <a href="/search/?searchtype=author&query=Barucci%2C+A">A. Barucci</a>, <a href="/search/?searchtype=author&query=Preusker%2C+F">F. Preusker</a>, <a href="/search/?searchtype=author&query=Scholten%2C+F">F. Scholten</a>, <a href="/search/?searchtype=author&query=Jorda%2C+L">L. Jorda</a>, <a href="/search/?searchtype=author&query=Pommerol%2C+A">A. Pommerol</a>, <a href="/search/?searchtype=author&query=Sierks%2C+H">H. Sierks</a>, <a href="/search/?searchtype=author&query=Agarwal%2C+J">J. Agarwal</a>, <a href="/search/?searchtype=author&query=A%27Hearn%2C+M">M. A'Hearn</a>, <a href="/search/?searchtype=author&query=Bertaux%2C+J+-">J. -L. Bertaux</a>, <a href="/search/?searchtype=author&query=Bertini%2C+I">I. Bertini</a>, <a href="/search/?searchtype=author&query=Boudreault%2C+S">S. Boudreault</a>, <a href="/search/?searchtype=author&query=Cremonese%2C+G">G. Cremonese</a>, <a href="/search/?searchtype=author&query=Da+Deppo%2C+V">V. Da Deppo</a>, <a href="/search/?searchtype=author&query=Davidsson%2C+B+J+R">B. J. R. Davidsson</a>, <a href="/search/?searchtype=author&query=Debei%2C+S">S. Debei</a>, <a href="/search/?searchtype=author&query=De+Cecco%2C+M">M. De Cecco</a>, <a href="/search/?searchtype=author&query=Deller%2C+J">J. Deller</a>, <a href="/search/?searchtype=author&query=Fulle%2C+M">M. Fulle</a>, <a href="/search/?searchtype=author&query=Giquel%2C+A">A. Giquel</a>, <a href="/search/?searchtype=author&query=Groussin%2C+O">O. Groussin</a>, <a href="/search/?searchtype=author&query=Gutierrez%2C+P+J">P. J. Gutierrez</a>, <a href="/search/?searchtype=author&query=G%C3%BCttler%2C+C">C. G眉ttler</a> , et al. (21 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="1611.00012v1-abstract-short" style="display: inline;"> We present the results of the photometric and spectrophotometric properties of the 67P/Churyumov-Gerasimenko nucleus derived with the OSIRIS instrument during the closest fly-by over the comet, which took place on 14 th February 2015 at a distance of {\~} 6 km from the surface. Several images covering the 0掳-33掳 phase angle range were acquired, and the spatial resolution achieved was 11 cm/pxl. Th… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1611.00012v1-abstract-full').style.display = 'inline'; document.getElementById('1611.00012v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1611.00012v1-abstract-full" style="display: none;"> We present the results of the photometric and spectrophotometric properties of the 67P/Churyumov-Gerasimenko nucleus derived with the OSIRIS instrument during the closest fly-by over the comet, which took place on 14 th February 2015 at a distance of {\~} 6 km from the surface. Several images covering the 0掳-33掳 phase angle range were acquired, and the spatial resolution achieved was 11 cm/pxl. The flown-by region is located on the big lobe of the comet, near the borders of the Ash, Apis and Imhotep regions. Our analysis shows that this region features local heterogeneities at the decimetre scale. We observed difference of reflectance up to 40{\%} between bright spots and sombre regions, and spectral slope variations up to 50{\%}. The spectral reddening effect observed globally on the comet surface by Fornasier et al. (2015) is also observed locally on this region, but with a less steep behaviour. We note that numerous metre-sized boulders, which exhibit a smaller opposition effect, also appear spectrally redder than their surroundings. In this region, we found no evidence linking observed bright spots to exposed water-ice-rich material. We fitted our dataset using the Hapke 2008 photometric model. The region overflown is globally as dark as the whole nucleus (geometric albedo of 6.8{\%}) and it has a high porosity value in the uppermost-layers (86{\%}). These results of the photometric analysis at a decimetre scale indicate that the photometric properties of the flown-by region are similar to those previously found for the whole nucleus. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1611.00012v1-abstract-full').style.display = 'none'; document.getElementById('1611.00012v1-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 October, 2016; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> November 2016. </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, 16 figures, 5 tables, (also presented at DPS48/ESPC11: http://cdsads.u-strasbg.fr/abs/2016DPS....4830004F)</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1609.07743">arXiv:1609.07743</a> <span> [<a href="https://arxiv.org/pdf/1609.07743">pdf</a>, <a href="https://arxiv.org/format/1609.07743">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/10.1093/mnras/stw2409">10.1093/mnras/stw2409 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Summer fireworks on comet 67P </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Vincent%2C+J+-">J. -B. Vincent</a>, <a href="/search/?searchtype=author&query=A%27Hearn%2C+M+F">M. F. A'Hearn</a>, <a href="/search/?searchtype=author&query=Lin%2C+Z+-">Z. -Y. Lin</a>, <a href="/search/?searchtype=author&query=El-Maarry%2C+M+R">M. R. El-Maarry</a>, <a href="/search/?searchtype=author&query=Pajola%2C+M">M. Pajola</a>, <a href="/search/?searchtype=author&query=Sierks%2C+H">H. Sierks</a>, <a href="/search/?searchtype=author&query=Barbieri%2C+C">C. Barbieri</a>, <a href="/search/?searchtype=author&query=Lamy%2C+P+L">P. L. Lamy</a>, <a href="/search/?searchtype=author&query=Rodrigo%2C+R">R. Rodrigo</a>, <a href="/search/?searchtype=author&query=Koschny%2C+D">D. Koschny</a>, <a href="/search/?searchtype=author&query=Rickman%2C+H">H. Rickman</a>, <a href="/search/?searchtype=author&query=Keller%2C+H+U">H. U. Keller</a>, <a href="/search/?searchtype=author&query=Agarwal%2C+J">J. Agarwal</a>, <a href="/search/?searchtype=author&query=Barucci%2C+M+A">M. A. Barucci</a>, <a href="/search/?searchtype=author&query=Bertaux%2C+J+-">J. -L. Bertaux</a>, <a href="/search/?searchtype=author&query=Bertini%2C+I">I. Bertini</a>, <a href="/search/?searchtype=author&query=Besse%2C+S">S. Besse</a>, <a href="/search/?searchtype=author&query=Bodewits%2C+D">D. Bodewits</a>, <a href="/search/?searchtype=author&query=Cremonese%2C+G">G. Cremonese</a>, <a href="/search/?searchtype=author&query=Da+Deppo%2C+V">V. Da Deppo</a>, <a href="/search/?searchtype=author&query=Davidsson%2C+B">B. Davidsson</a>, <a href="/search/?searchtype=author&query=Debei%2C+S">S. Debei</a>, <a href="/search/?searchtype=author&query=De+Cecco%2C+M">M. De Cecco</a>, <a href="/search/?searchtype=author&query=Deller%2C+J">J. Deller</a>, <a href="/search/?searchtype=author&query=Fornasier%2C+S">S. Fornasier</a> , et al. (30 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="1609.07743v1-abstract-short" style="display: inline;"> During its two years mission around comet 67P/Churyumov-Gerasimenko, ESA's Rosetta spacecraft had the unique opportunity to follow closely a comet in the most active part of its orbit. Many studies have presented the typical features associated to the activity of the nucleus, such as localized dust and gas jets. Here we report on series of more energetic transient events observed during the three… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1609.07743v1-abstract-full').style.display = 'inline'; document.getElementById('1609.07743v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1609.07743v1-abstract-full" style="display: none;"> During its two years mission around comet 67P/Churyumov-Gerasimenko, ESA's Rosetta spacecraft had the unique opportunity to follow closely a comet in the most active part of its orbit. Many studies have presented the typical features associated to the activity of the nucleus, such as localized dust and gas jets. Here we report on series of more energetic transient events observed during the three months surrounding the comet's perihelion passage in August 2015. We detected and characterized 34 outbursts with the Rosetta cameras, one every 2.4 nucleus rotation. We identified 3 main dust plume morphologies associated to these events: a narrow jet, a broad fan, and more complex plumes featuring both previous types together. These plumes are comparable in scale and temporal variation to what has been observed on other comets. We present a map of the outbursts source locations, and discuss the associated topography. We find that the spatial distribution sources on the nucleus correlates well with morphological region boundaries, especially in areas marked by steep scarps or cliffs. Outbursts occur either in the early morning or shortly after the local noon, indicating two potential processes: Morning outbursts may be triggered by thermal stresses linked to the rapid change of temperature, afternoon events are most likely related to the diurnal or seasonal heat wave reaching volatiles buried under the first surface layer. In addition, we propose that some events can be the result of a completely different mechanism, in which most of the dust is released upon the collapse of a cliff. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1609.07743v1-abstract-full').style.display = 'none'; document.getElementById('1609.07743v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 25 September, 2016; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> September 2016. </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">MNRAS (2016)</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1609.00551">arXiv:1609.00551</a> <span> [<a href="https://arxiv.org/pdf/1609.00551">pdf</a>, <a href="https://arxiv.org/format/1609.00551">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/10.1051/0004-6361/201628764">10.1051/0004-6361/201628764 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Detection of exposed H$_2$O ice on the nucleus of comet 67P/Churyumov-Gerasimenko </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Barucci%2C+M+A">M. A. Barucci</a>, <a href="/search/?searchtype=author&query=Filacchione%2C+G">G. Filacchione</a>, <a href="/search/?searchtype=author&query=Fornasier%2C+S">S. Fornasier</a>, <a href="/search/?searchtype=author&query=Raponi%2C+A">A. Raponi</a>, <a href="/search/?searchtype=author&query=Deshapriya%2C+J+D+P">J. D. P. Deshapriya</a>, <a href="/search/?searchtype=author&query=Tosi%2C+F">F. Tosi</a>, <a href="/search/?searchtype=author&query=Feller%2C+C">C. Feller</a>, <a href="/search/?searchtype=author&query=Ciarniello%2C+M">M. Ciarniello</a>, <a href="/search/?searchtype=author&query=Sierks%2C+H">H. Sierks</a>, <a href="/search/?searchtype=author&query=Capaccioni%2C+F">F. Capaccioni</a>, <a href="/search/?searchtype=author&query=Pommerol%2C+A">A. Pommerol</a>, <a href="/search/?searchtype=author&query=Massironi%2C+M">M. Massironi</a>, <a href="/search/?searchtype=author&query=Oklay%2C+N">N. Oklay</a>, <a href="/search/?searchtype=author&query=Merlin%2C+F">F. Merlin</a>, <a href="/search/?searchtype=author&query=Vincent%2C+J+-">J. -B. Vincent</a>, <a href="/search/?searchtype=author&query=Fulchignoni%2C+M">M. Fulchignoni</a>, <a href="/search/?searchtype=author&query=Guilbert-Lepoutre%2C+A">A. Guilbert-Lepoutre</a>, <a href="/search/?searchtype=author&query=Perna%2C+D">D. Perna</a>, <a href="/search/?searchtype=author&query=Capria%2C+M+T">M. T. Capria</a>, <a href="/search/?searchtype=author&query=Hasselmann%2C+P+H">P. H. Hasselmann</a>, <a href="/search/?searchtype=author&query=Rousseau%2C+B">B. Rousseau</a>, <a href="/search/?searchtype=author&query=Barbieri%2C+C">C. Barbieri</a>, <a href="/search/?searchtype=author&query=Bockelee-Morvan%2C+D">D. Bockelee-Morvan</a>, <a href="/search/?searchtype=author&query=Lamy%2C+P+L">P. L. Lamy</a>, <a href="/search/?searchtype=author&query=De+Sanctis%2C+C">C. De Sanctis</a> , et al. (20 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="1609.00551v1-abstract-short" style="display: inline;"> Since the orbital insertion of the Rosetta spacecraft, comet 67P/Churyumov-Gerasimenko (67P/C-G) has been mapped by OSIRIS camera and VIRTIS spectro-imager, producing a huge quantity of images and spectra of the comet's nucleus. The aim of this work is to search for the presence of H$_2$O on the nucleus which, in general, appears very dark and rich in dehydrated organic material. After selecting i… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1609.00551v1-abstract-full').style.display = 'inline'; document.getElementById('1609.00551v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1609.00551v1-abstract-full" style="display: none;"> Since the orbital insertion of the Rosetta spacecraft, comet 67P/Churyumov-Gerasimenko (67P/C-G) has been mapped by OSIRIS camera and VIRTIS spectro-imager, producing a huge quantity of images and spectra of the comet's nucleus. The aim of this work is to search for the presence of H$_2$O on the nucleus which, in general, appears very dark and rich in dehydrated organic material. After selecting images of the bright spots which could be good candidates to search for H$_2$O ice, taken at high resolution by OSIRIS, we check for spectral cubes of the selected coordinates to identify these spots observed by VIRTIS. The selected OSIRIS images were processed with the OSIRIS standard pipeline and corrected for the illumination conditions for each pixel using the Lommel-Seeliger disk law. The spots with higher I/F were selected and then analysed spectrophotometrically and compared with the surrounding area. We selected 13 spots as good targets to be analysed by VIRTIS to search for the 2 micron absorption band of water ice in the VIRTIS spectral cubes. Out of the 13 selected bright spots, eight of them present positive H$_2$O ice detection on the VIRTIS data. A spectral analysis was performed and the approximate temperature of each spot was computed. The H$_2$O ice content was confirmed by modeling the spectra with mixing (areal and intimate) of H$_2$O ice and dark terrain, using Hapke's radiative transfer modeling. We also present a detailed analysis of the detected spots. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1609.00551v1-abstract-full').style.display = 'none'; document.getElementById('1609.00551v1-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 September, 2016; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> September 2016. </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">paper in press in A&A, 13 pages, 6 figures</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> A&A 595, A102 (2016) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1608.08774">arXiv:1608.08774</a> <span> [<a href="https://arxiv.org/pdf/1608.08774">pdf</a>, <a href="https://arxiv.org/ps/1608.08774">ps</a>, <a href="https://arxiv.org/format/1608.08774">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/10.1093/mnras/stw2117">10.1093/mnras/stw2117 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Sublimation of icy aggregates in the coma of comet 67P/Churyumov-Gerasimenko detected with the OSIRIS cameras onboard Rosetta </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Gicquel%2C+A">A. Gicquel</a>, <a href="/search/?searchtype=author&query=Vincent%2C+J+-">J. -B. Vincent</a>, <a href="/search/?searchtype=author&query=Agarwal%2C+J">J. Agarwal</a>, <a href="/search/?searchtype=author&query=A%27Hearn%2C+M+F">M. F. A'Hearn</a>, <a href="/search/?searchtype=author&query=Bertini%2C+I">I. Bertini</a>, <a href="/search/?searchtype=author&query=Bodewits%2C+D">D. Bodewits</a>, <a href="/search/?searchtype=author&query=Sierks%2C+H">H. Sierks</a>, <a href="/search/?searchtype=author&query=Lin%2C+Z+-">Z. -Y. Lin</a>, <a href="/search/?searchtype=author&query=Barbieri%2C+C">C. Barbieri</a>, <a href="/search/?searchtype=author&query=Lamy%2C+P+L">P. L. Lamy</a>, <a href="/search/?searchtype=author&query=Rodrigo%2C+R">R. Rodrigo</a>, <a href="/search/?searchtype=author&query=Koschny%2C+D">D. Koschny</a>, <a href="/search/?searchtype=author&query=Rickman%2C+H">H. Rickman</a>, <a href="/search/?searchtype=author&query=Keller%2C+H+U">H. U. Keller</a>, <a href="/search/?searchtype=author&query=Barucci%2C+M+A">M. A. Barucci</a>, <a href="/search/?searchtype=author&query=Bertaux%2C+J+-">J. -L. Bertaux</a>, <a href="/search/?searchtype=author&query=Besse%2C+S">S. Besse</a>, <a href="/search/?searchtype=author&query=Cremonese%2C+G">G. Cremonese</a>, <a href="/search/?searchtype=author&query=Da+Deppo%2C+V">V. Da Deppo</a>, <a href="/search/?searchtype=author&query=Davidsson%2C+B">B. Davidsson</a>, <a href="/search/?searchtype=author&query=Debei%2C+S">S. Debei</a>, <a href="/search/?searchtype=author&query=Deller%2C+J">J. Deller</a>, <a href="/search/?searchtype=author&query=De+Cecco%2C+M">M. De Cecco</a>, <a href="/search/?searchtype=author&query=Frattin%2C+E">E. Frattin</a>, <a href="/search/?searchtype=author&query=El-Maarry%2C+M+R">M. R. El-Maarry</a> , et al. (36 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="1608.08774v1-abstract-short" style="display: inline;"> Beginning in March 2014, the OSIRIS (Optical, Spectroscopic, and Infrared Remote Imaging System) cameras began capturing images of the nucleus and coma (gas and dust) of comet 67P/Churyumov-Gerasimenko using both the wide angle camera (WAC) and the narrow angle camera (NAC). The many observations taken since July of 2014 have been used to study the morphology, location, and temporal variation of t… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1608.08774v1-abstract-full').style.display = 'inline'; document.getElementById('1608.08774v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1608.08774v1-abstract-full" style="display: none;"> Beginning in March 2014, the OSIRIS (Optical, Spectroscopic, and Infrared Remote Imaging System) cameras began capturing images of the nucleus and coma (gas and dust) of comet 67P/Churyumov-Gerasimenko using both the wide angle camera (WAC) and the narrow angle camera (NAC). The many observations taken since July of 2014 have been used to study the morphology, location, and temporal variation of the comet's dust jets. We analyzed the dust monitoring observations shortly after the southern vernal equinox on May 30 and 31, 2015 with the WAC at the heliocentric distance Rh = 1.53 AU, where it is possible to observe that the jet rotates with the nucleus. We found that the decline of brightness as a function of the distance of the jet is much steeper than the background coma, which is a first indication of sublimation. We adapted a model of sublimation of icy aggregates and studied the effect as a function of the physical properties of the aggregates (composition and size). The major finding of this article was that through the sublimation of the aggregates of dirty grains (radius a between 5 microm and 50 microm) we were able to completely reproduce the radial brightness profile of a jet beyond 4 km from the nucleus. To reproduce the data we needed to inject a number of aggregates between 8.5 x $10^{13}$ and 8.5 x $10^{10}$ for a = 5 microm and 50 microm respectively, or an initial mass of $H_2O$ ice around 22kg. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1608.08774v1-abstract-full').style.display = 'none'; document.getElementById('1608.08774v1-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 August, 2016; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> August 2016. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">11 pages, 7 figures, 3 tables, special issue "The ESLAB 50 Symposium - spacecraft at comets from 1P/Halley to 67P/Churyumov-Gerasimenko" in the 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/1608.07933">arXiv:1608.07933</a> <span> [<a href="https://arxiv.org/pdf/1608.07933">pdf</a>, <a href="https://arxiv.org/format/1608.07933">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/10.1093/mnras/stw2179">10.1093/mnras/stw2179 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Acceleration of Individual, Decimetre-sized Aggregates in the Lower Coma of Comet 67P/Churyumov-Gerasimenko </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Agarwal%2C+J">J. Agarwal</a>, <a href="/search/?searchtype=author&query=A%27Hearn%2C+M+F">M. F. A'Hearn</a>, <a href="/search/?searchtype=author&query=Vincent%2C+J+-">J. -B. Vincent</a>, <a href="/search/?searchtype=author&query=Guettler%2C+C">C. Guettler</a>, <a href="/search/?searchtype=author&query=Hoefner%2C+S">S. Hoefner</a>, <a href="/search/?searchtype=author&query=Sierks%2C+H">H. Sierks</a>, <a href="/search/?searchtype=author&query=Tubiana%2C+C">C. Tubiana</a>, <a href="/search/?searchtype=author&query=Barbieri%2C+C">C. Barbieri</a>, <a href="/search/?searchtype=author&query=Lamy%2C+P+L">P. L. Lamy</a>, <a href="/search/?searchtype=author&query=Rodrigo%2C+R">R. Rodrigo</a>, <a href="/search/?searchtype=author&query=Koschny%2C+D">D. Koschny</a>, <a href="/search/?searchtype=author&query=Rickman%2C+H">H. Rickman</a>, <a href="/search/?searchtype=author&query=Barucci%2C+M+A">M. A. Barucci</a>, <a href="/search/?searchtype=author&query=Bertaux%2C+J+-">J. -L. Bertaux</a>, <a href="/search/?searchtype=author&query=Bertini%2C+I">I. Bertini</a>, <a href="/search/?searchtype=author&query=Boudreault%2C+S">S. Boudreault</a>, <a href="/search/?searchtype=author&query=Cremonese%2C+G">G. Cremonese</a>, <a href="/search/?searchtype=author&query=Da+Deppo%2C+V">V. Da Deppo</a>, <a href="/search/?searchtype=author&query=Davidsson%2C+B">B. Davidsson</a>, <a href="/search/?searchtype=author&query=Debei%2C+S">S. Debei</a>, <a href="/search/?searchtype=author&query=De+Cecco%2C+M">M. De Cecco</a>, <a href="/search/?searchtype=author&query=Deller%2C+J">J. Deller</a>, <a href="/search/?searchtype=author&query=Fornasier%2C+S">S. Fornasier</a>, <a href="/search/?searchtype=author&query=Fulle%2C+M">M. Fulle</a>, <a href="/search/?searchtype=author&query=Gicquel%2C+A">A. Gicquel</a> , et al. (19 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="1608.07933v1-abstract-short" style="display: inline;"> We present OSIRIS/NAC observations of decimetre-sized, likely ice-containing aggregates ejected from a confined region on the surface of comet 67P/Churyumov-Gerasimenko. The images were obtained in January 2016 when the comet was at 2 AU from the Sun out-bound from perihelion. We measure the acceleration of individual aggregates through a two-hour image series. Approximately 50% of the aggregates… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1608.07933v1-abstract-full').style.display = 'inline'; document.getElementById('1608.07933v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1608.07933v1-abstract-full" style="display: none;"> We present OSIRIS/NAC observations of decimetre-sized, likely ice-containing aggregates ejected from a confined region on the surface of comet 67P/Churyumov-Gerasimenko. The images were obtained in January 2016 when the comet was at 2 AU from the Sun out-bound from perihelion. We measure the acceleration of individual aggregates through a two-hour image series. Approximately 50% of the aggregates are accelerated away from the nucleus, and 50% towards it, and likewise towards either horizontal direction. The accelerations are up to one order of magnitude stronger than local gravity, and are most simply explained by the combined effect of gas drag accelerating all aggregates upwards, and the recoil force from asymmetric outgassing, either from rotating aggregates with randomly oriented spin axes and sufficient thermal inertia to shift the temperature maximum away from an aggregate's subsolar region, or from aggregates with variable ice content. At least 10% of the aggregates will escape the gravity field of the nucleus and feed the comet's debris trail, while others may fall back to the surface and contribute to the deposits covering parts of the northern hemisphere. The rocket force plays a crucial role in pushing these aggregates back towards the surface. Our observations show the future back fall material in the process of ejection, and provide the first direct measurement of the acceleration of aggregates in the innermost coma (<2km) of a comet, where gas drag is still significant. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1608.07933v1-abstract-full').style.display = 'none'; document.getElementById('1608.07933v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 29 August, 2016; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> August 2016. </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, 14 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/1607.05632">arXiv:1607.05632</a> <span> [<a href="https://arxiv.org/pdf/1607.05632">pdf</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/10.3847/0004-6256/152/5/130">10.3847/0004-6256/152/5/130 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Changes in the physical environment of the inner coma of 67P/Churyumov-Gerasimenko with decreasing heliocentric distance </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Bodewits%2C+D">D. Bodewits</a>, <a href="/search/?searchtype=author&query=Lara%2C+L+M">L. M. Lara</a>, <a href="/search/?searchtype=author&query=A%27Hearn%2C+M+F">M. F. A'Hearn</a>, <a href="/search/?searchtype=author&query=La+Forgia%2C+F">F. La Forgia</a>, <a href="/search/?searchtype=author&query=Giquel%2C+A">A. Giquel</a>, <a href="/search/?searchtype=author&query=Kovacs%2C+G">G. Kovacs</a>, <a href="/search/?searchtype=author&query=Knollenberg%2C+J">J. Knollenberg</a>, <a href="/search/?searchtype=author&query=Lazzarin%2C+M">M. Lazzarin</a>, <a href="/search/?searchtype=author&query=Lin%2C+Z+-">Z. -Y. Lin</a>, <a href="/search/?searchtype=author&query=Shi%2C+X">X. Shi</a>, <a href="/search/?searchtype=author&query=Snodgrass%2C+C">C. Snodgrass</a>, <a href="/search/?searchtype=author&query=Tubiana%2C+C">C. Tubiana</a>, <a href="/search/?searchtype=author&query=Sierks%2C+H">H. Sierks</a>, <a href="/search/?searchtype=author&query=Barbieri%2C+C">C. Barbieri</a>, <a href="/search/?searchtype=author&query=Lamy%2C+P+M">P. M. Lamy</a>, <a href="/search/?searchtype=author&query=Rodrigo%2C+R">R. Rodrigo</a>, <a href="/search/?searchtype=author&query=Koschny%2C+D">D. Koschny</a>, <a href="/search/?searchtype=author&query=Rickman%2C+H">H. Rickman</a>, <a href="/search/?searchtype=author&query=Keller%2C+H+U">H. U. Keller</a>, <a href="/search/?searchtype=author&query=Barucci%2C+M+A">M. A. Barucci</a>, <a href="/search/?searchtype=author&query=Bertaux%2C+J+-">J. -L. Bertaux</a>, <a href="/search/?searchtype=author&query=Bertini%2C+I">I. Bertini</a>, <a href="/search/?searchtype=author&query=Boudreault%2C+S">S. Boudreault</a>, <a href="/search/?searchtype=author&query=Cremonese%2C+G">G. Cremonese</a>, <a href="/search/?searchtype=author&query=DaDeppo%2C+V">V. DaDeppo</a> , et al. (21 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="1607.05632v1-abstract-short" style="display: inline;"> The Wide Angle Camera of the OSIRIS instrument on board the Rosetta spacecraft is equipped with several narrowband filters that are centered on the emission lines and bands of various fragment species. These are used to determine the evolution of the production and spatial distribution of the gas in the inner coma of comet 67P with time and heliocentric distance, here between 2.6 - 1.3 AU pre-peri… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1607.05632v1-abstract-full').style.display = 'inline'; document.getElementById('1607.05632v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1607.05632v1-abstract-full" style="display: none;"> The Wide Angle Camera of the OSIRIS instrument on board the Rosetta spacecraft is equipped with several narrowband filters that are centered on the emission lines and bands of various fragment species. These are used to determine the evolution of the production and spatial distribution of the gas in the inner coma of comet 67P with time and heliocentric distance, here between 2.6 - 1.3 AU pre-perihelion. Our observations indicate that the emission observed in the OH, OI, CN, NH, and NH2 filters is mostly produced by dissociative electron impact excitation of different parent species. We conclude that CO2 rather than H2O is a significant source of the [OI] 630 nm emission. A strong plume-like feature observed in the in CN and [OI] filters is present throughout our observations. This plume is not present in OH emission and indicates a local enhancement of the CO2/H2O ratio by as much as a factor of 3. We observed a sudden decrease in intensity levels after March 2015, which we attribute to decreased electron temperatures in the first kilometers above the nucleus surface. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1607.05632v1-abstract-full').style.display = 'none'; document.getElementById('1607.05632v1-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, 2016; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> July 2016. </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 figures, 6 tables</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1605.02095">arXiv:1605.02095</a> <span> [<a href="https://arxiv.org/pdf/1605.02095">pdf</a>, <a href="https://arxiv.org/ps/1605.02095">ps</a>, <a href="https://arxiv.org/format/1605.02095">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/10.1051/0004-6361/201527784">10.1051/0004-6361/201527784 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Observations and analysis of a curved jet in the coma of comet 67P/Churyumov-Gerasimenko </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Lin%2C+Z">Zhong-Yi Lin</a>, <a href="/search/?searchtype=author&query=Lai%2C+I+-">I. -L. Lai</a>, <a href="/search/?searchtype=author&query=Su%2C+C+-">C. -C. Su</a>, <a href="/search/?searchtype=author&query=Ip%2C+W+-">W. -H. Ip</a>, <a href="/search/?searchtype=author&query=Lee%2C+J+-">J. -C. Lee</a>, <a href="/search/?searchtype=author&query=Wu%2C+J+-">J. -S. Wu</a>, <a href="/search/?searchtype=author&query=Vincent%2C+J+-">J. -B. Vincent</a>, <a href="/search/?searchtype=author&query=La+Forgia%2C+F">F. La Forgia</a>, <a href="/search/?searchtype=author&query=Sierks%2C+H">H. Sierks</a>, <a href="/search/?searchtype=author&query=Barbieri%2C+C">C. Barbieri</a>, <a href="/search/?searchtype=author&query=Lamy%2C+P+L">P. L. Lamy</a>, <a href="/search/?searchtype=author&query=Rodrigo%2C+R">R. Rodrigo</a>, <a href="/search/?searchtype=author&query=Koschny%2C+D">D. Koschny</a>, <a href="/search/?searchtype=author&query=Rickman%2C+H">H. Rickman</a>, <a href="/search/?searchtype=author&query=Keller%2C+H+U">H. U. Keller</a>, <a href="/search/?searchtype=author&query=Agarwal%2C+J">J. Agarwal</a>, <a href="/search/?searchtype=author&query=A%27Hearn%2C+M+F">M. F. A'Hearn</a>, <a href="/search/?searchtype=author&query=Barucci%2C+M+A">M. A. Barucci</a>, <a href="/search/?searchtype=author&query=Bertaux%2C+J+-">J. -L. Bertaux</a>, <a href="/search/?searchtype=author&query=Bertini%2C+I">I. Bertini</a>, <a href="/search/?searchtype=author&query=Bodewits%2C+D">D. Bodewits</a>, <a href="/search/?searchtype=author&query=Cremonese%2C+G">G. Cremonese</a>, <a href="/search/?searchtype=author&query=Da+Deppo%2C+V">V. Da Deppo</a>, <a href="/search/?searchtype=author&query=Davidsson%2C+B">B. Davidsson</a>, <a href="/search/?searchtype=author&query=Debet%2C+S">S. Debet</a> , et al. (26 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="1605.02095v1-abstract-short" style="display: inline;"> We analyze the physical properties and dynamical origin of a curved jet of comet 67P/Churyumov-Gerasimenko that was observed repeatedly in several nucleus rotations starting on May 30 and persisting until early August, 2015. We simulated the motion of dust grains ejected from the nucleus surface under the influence of the gravity and viscous drag effect of the expanding gas flow from the rotating… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1605.02095v1-abstract-full').style.display = 'inline'; document.getElementById('1605.02095v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1605.02095v1-abstract-full" style="display: none;"> We analyze the physical properties and dynamical origin of a curved jet of comet 67P/Churyumov-Gerasimenko that was observed repeatedly in several nucleus rotations starting on May 30 and persisting until early August, 2015. We simulated the motion of dust grains ejected from the nucleus surface under the influence of the gravity and viscous drag effect of the expanding gas flow from the rotating nucleus. The formation of the curved jet is a combination of the size of the dust particles (~0.1-1 mm) and the location of the source region near the nucleus equator. This enhances the spiral feature of the collimated dust stream after the dust is accelerated to a terminal speed on the order of m/s. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1605.02095v1-abstract-full').style.display = 'none'; document.getElementById('1605.02095v1-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, 2016; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> May 2016. </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">5pages, 5 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/1602.01965">arXiv:1602.01965</a> <span> [<a href="https://arxiv.org/pdf/1602.01965">pdf</a>, <a href="https://arxiv.org/ps/1602.01965">ps</a>, <a href="https://arxiv.org/format/1602.01965">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/10.1051/0004-6361/201527564">10.1051/0004-6361/201527564 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> The dust environment of comet 67P/Churyumov-Gerasimenko from Rosetta OSIRIS and VLT observations in the 4.5 to 2.9 au heliocentric distance range inbound </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Moreno%2C+F">F. Moreno</a>, <a href="/search/?searchtype=author&query=Snodgrass%2C+C">C. Snodgrass</a>, <a href="/search/?searchtype=author&query=Hainaut%2C+O">O. Hainaut</a>, <a href="/search/?searchtype=author&query=Tubiana%2C+C">C. Tubiana</a>, <a href="/search/?searchtype=author&query=Sierks%2C+H">H. Sierks</a>, <a href="/search/?searchtype=author&query=Barbieri%2C+C">C. Barbieri</a>, <a href="/search/?searchtype=author&query=Lamy%2C+P+L">P. L. Lamy</a>, <a href="/search/?searchtype=author&query=Rodrigo%2C+R">R. Rodrigo</a>, <a href="/search/?searchtype=author&query=Koschny%2C+D">D. Koschny</a>, <a href="/search/?searchtype=author&query=Rickman%2C+H">H. Rickman</a>, <a href="/search/?searchtype=author&query=Keller%2C+H+U">H. U. Keller</a>, <a href="/search/?searchtype=author&query=Agarwal%2C+J">J. Agarwal</a>, <a href="/search/?searchtype=author&query=AHearn%2C+M+F">M. F. AHearn</a>, <a href="/search/?searchtype=author&query=Barucci%2C+M+A">M. A. Barucci</a>, <a href="/search/?searchtype=author&query=Bertaux%2C+J+L">J. L. Bertaux</a>, <a href="/search/?searchtype=author&query=Bertini%2C+I">I. Bertini</a>, <a href="/search/?searchtype=author&query=Besse%2C+S">S. Besse</a>, <a href="/search/?searchtype=author&query=Bodewits%2C+D">D. Bodewits</a>, <a href="/search/?searchtype=author&query=Cremonese%2C+G">G. Cremonese</a>, <a href="/search/?searchtype=author&query=Da+Deppo%2C+V">V. Da Deppo</a>, <a href="/search/?searchtype=author&query=Davidsson%2C+B">B. Davidsson</a>, <a href="/search/?searchtype=author&query=Debei%2C+S">S. Debei</a>, <a href="/search/?searchtype=author&query=De+Cecco%2C+M">M. De Cecco</a>, <a href="/search/?searchtype=author&query=Ferri%2C+F">F. Ferri</a>, <a href="/search/?searchtype=author&query=Fornasier%2C+S">S. Fornasier</a> , et al. (29 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="1602.01965v1-abstract-short" style="display: inline;"> The ESA Rosetta spacecraft, currently orbiting around comet 67P, has already provided in situ measurements of the dust grain properties from several instruments, particularly OSIRIS and GIADA. We propose adding value to those measurements by combining them with ground-based observations of the dust tail to monitor the overall, time-dependent dust-production rate and size distribution. To constrain… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1602.01965v1-abstract-full').style.display = 'inline'; document.getElementById('1602.01965v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1602.01965v1-abstract-full" style="display: none;"> The ESA Rosetta spacecraft, currently orbiting around comet 67P, has already provided in situ measurements of the dust grain properties from several instruments, particularly OSIRIS and GIADA. We propose adding value to those measurements by combining them with ground-based observations of the dust tail to monitor the overall, time-dependent dust-production rate and size distribution. To constrain the dust grain properties, we take Rosetta OSIRIS and GIADA results into account, and combine OSIRIS data during the approach phase (from late April to early June 2014) with a large data set of ground-based images that were acquired with the ESO Very Large Telescope (VLT) from February to November 2014. A Monte Carlo dust tail code has been applied to retrieve the dust parameters. Key properties of the grains (density, velocity, and size distribution) were obtained from Rosetta observations: these parameters were used as input of the code to considerably reduce the number of free parameters. In this way, the overall dust mass-loss rate and its dependence on the heliocentric distance could be obtained accurately. The dust parameters derived from the inner coma measurements by OSIRIS and GIADA and from distant imaging using VLT data are consistent, except for the power index of the size-distribution function, which is $伪$=--3, instead of $伪$=--2, for grains smaller than 1 mm. This is possibly linked to the presence of fluffy aggregates in the coma. The onset of cometary activity occurs at approximately 4.3 au, with a dust production rate of 0.5 kg/s, increasing up to 15 kg/s at 2.9 au. This implies a dust-to-gas mass ratio varying between 3.8 and 6.5 for the best-fit model when combined with water-production rates from the MIRO experiment. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1602.01965v1-abstract-full').style.display = 'none'; document.getElementById('1602.01965v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 5 February, 2016; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> February 2016. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">Accepted by Astronomy and Astrophysics (January 17th, 2016)</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1512.03193">arXiv:1512.03193</a> <span> [<a href="https://arxiv.org/pdf/1512.03193">pdf</a>, <a href="https://arxiv.org/format/1512.03193">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/10.1051/0004-6361/201527159">10.1051/0004-6361/201527159 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Are fractured cliffs the source of cometary dust jets ? Insights from OSIRIS/Rosetta at 67P </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Vincent%2C+J+-">J. -B. Vincent</a>, <a href="/search/?searchtype=author&query=Oklay%2C+N">N. Oklay</a>, <a href="/search/?searchtype=author&query=Pajola%2C+M">M. Pajola</a>, <a href="/search/?searchtype=author&query=H%C3%B6fner%2C+S">S. H枚fner</a>, <a href="/search/?searchtype=author&query=Sierks%2C+H">H. Sierks</a>, <a href="/search/?searchtype=author&query=Hu%2C+X">X. Hu</a>, <a href="/search/?searchtype=author&query=Barbieri%2C+C">C. Barbieri</a>, <a href="/search/?searchtype=author&query=Lamy%2C+P+L">P. L. Lamy</a>, <a href="/search/?searchtype=author&query=Rodrigo%2C+R">R. Rodrigo</a>, <a href="/search/?searchtype=author&query=Koschny%2C+D">D. Koschny</a>, <a href="/search/?searchtype=author&query=Rickman%2C+H">H. Rickman</a>, <a href="/search/?searchtype=author&query=Keller%2C+H+U">H. U. Keller</a>, <a href="/search/?searchtype=author&query=A%27Hearn%2C+M+F">M. F. A'Hearn</a>, <a href="/search/?searchtype=author&query=Barucci%2C+M+A">M. A. Barucci</a>, <a href="/search/?searchtype=author&query=Bertaux%2C+J+-">J. -L. Bertaux</a>, <a href="/search/?searchtype=author&query=Bertini%2C+I">I. Bertini</a>, <a href="/search/?searchtype=author&query=Besse%2C+S">S. Besse</a>, <a href="/search/?searchtype=author&query=Bodewits%2C+D">D. Bodewits</a>, <a href="/search/?searchtype=author&query=Cremonese%2C+G">G. Cremonese</a>, <a href="/search/?searchtype=author&query=Da+Deppo%2C+V">V. Da Deppo</a>, <a href="/search/?searchtype=author&query=Davidsson%2C+B">B. Davidsson</a>, <a href="/search/?searchtype=author&query=Debei%2C+S">S. Debei</a>, <a href="/search/?searchtype=author&query=De+Cecco%2C+M">M. De Cecco</a>, <a href="/search/?searchtype=author&query=El-Maarry%2C+M+R">M. R. El-Maarry</a>, <a href="/search/?searchtype=author&query=Fornasier%2C+S">S. Fornasier</a> , et al. (30 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="1512.03193v2-abstract-short" style="display: inline;"> Dust jets, i.e. fuzzy collimated streams of cometary material arising from the nucleus, have been observed in-situ on all comets since the Giotto mission flew by comet 1P/Halley in 1986. Yet their formation mechanism remains unknown. Several solutions have been proposed, from localized physical mechanisms on the surface/sub-surface (see review in Belton (2010)) to purely dynamical processes involv… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1512.03193v2-abstract-full').style.display = 'inline'; document.getElementById('1512.03193v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1512.03193v2-abstract-full" style="display: none;"> Dust jets, i.e. fuzzy collimated streams of cometary material arising from the nucleus, have been observed in-situ on all comets since the Giotto mission flew by comet 1P/Halley in 1986. Yet their formation mechanism remains unknown. Several solutions have been proposed, from localized physical mechanisms on the surface/sub-surface (see review in Belton (2010)) to purely dynamical processes involving the focusing of gas flows by the local topography (Crifo et al. 2002). While the latter seems to be responsible for the larger features, high resolution imagery has shown that broad streams are composed of many smaller features (a few meters wide) that connect directly to the nucleus surface. We monitored these jets at high resolution and over several months to understand what are the physical processes driving their formation, and how this affects the surface. Using many images of the same areas with different viewing angles, we performed a 3-dimensional reconstruction of collimated jets, and linked them precisely to their sources on the nucleus. Results.We show here observational evidence that the Northern hemisphere jets of comet 67P arise from areas with sharp topographic changes and describe the physical processes involved. We propose a model in which active cliffs are the main source of jet-like features, and therefore the regions eroding the fastest on comets. We suggest that this is a common mechanism taking place on all comets. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1512.03193v2-abstract-full').style.display = 'none'; document.getElementById('1512.03193v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 11 December, 2015; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 10 December, 2015; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> December 2015. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">Accepted by Astronomy & Astrophysics on 4 December 2015</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> A&A 587, A14 (2016) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1509.02794">arXiv:1509.02794</a> <span> [<a href="https://arxiv.org/pdf/1509.02794">pdf</a>, <a href="https://arxiv.org/format/1509.02794">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/10.1051/0004-6361/201527020">10.1051/0004-6361/201527020 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Temporal morphological changes in the Imhotep region of comet 67P/Churyumov-Gerasimenko </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Groussin%2C+O">O. Groussin</a>, <a href="/search/?searchtype=author&query=Sierks%2C+H">H. Sierks</a>, <a href="/search/?searchtype=author&query=Barbieri%2C+C">C. Barbieri</a>, <a href="/search/?searchtype=author&query=Lamy%2C+P">P. Lamy</a>, <a href="/search/?searchtype=author&query=Rodrigo%2C+R">R. Rodrigo</a>, <a href="/search/?searchtype=author&query=Koschny%2C+D">D. Koschny</a>, <a href="/search/?searchtype=author&query=Rickman%2C+H">H. Rickman</a>, <a href="/search/?searchtype=author&query=Keller%2C+H+U">H. U. Keller</a>, <a href="/search/?searchtype=author&query=Hearn%2C+M+F+A">M. F. A Hearn</a>, <a href="/search/?searchtype=author&query=Auger%2C+A+-">A. -T. Auger</a>, <a href="/search/?searchtype=author&query=Barucci%2C+M+A">M. A. Barucci</a>, <a href="/search/?searchtype=author&query=Bertaux%2C+J+-">J. -L. Bertaux</a>, <a href="/search/?searchtype=author&query=Bertini%2C+I">I. Bertini</a>, <a href="/search/?searchtype=author&query=Besse%2C+S">S. Besse</a>, <a href="/search/?searchtype=author&query=Cremonese%2C+G">G. Cremonese</a>, <a href="/search/?searchtype=author&query=Da+Deppo%2C+V">V. Da Deppo</a>, <a href="/search/?searchtype=author&query=Davidsson%2C+B">B. Davidsson</a>, <a href="/search/?searchtype=author&query=Debei%2C+S">S. Debei</a>, <a href="/search/?searchtype=author&query=De+Cecco%2C+M">M. De Cecco</a>, <a href="/search/?searchtype=author&query=El-Maarry%2C+M+R">M. R. El-Maarry</a>, <a href="/search/?searchtype=author&query=Fornasier%2C+S">S. Fornasier</a>, <a href="/search/?searchtype=author&query=Fulle%2C+M">M. Fulle</a>, <a href="/search/?searchtype=author&query=Guti%C3%A9rrez%2C+P+J">P. J. Guti茅rrez</a>, <a href="/search/?searchtype=author&query=G%C3%BCttler%2C+C">C. G眉ttler</a>, <a href="/search/?searchtype=author&query=Hviid%2C+S">S. Hviid</a> , et al. (23 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="1509.02794v1-abstract-short" style="display: inline;"> We report on the first major temporal morphological changes observed on the surface of the nucleus of comet 67P/Churyumov-Gerasimenko, in the smooth terrains of the Imhotep region. We use images of the OSIRIS cameras onboard Rosetta to follow the temporal changes from 24 May 2015 to 11 July 2015. The morphological changes observed on the surface are visible in the form of roundish features, which… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1509.02794v1-abstract-full').style.display = 'inline'; document.getElementById('1509.02794v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1509.02794v1-abstract-full" style="display: none;"> We report on the first major temporal morphological changes observed on the surface of the nucleus of comet 67P/Churyumov-Gerasimenko, in the smooth terrains of the Imhotep region. We use images of the OSIRIS cameras onboard Rosetta to follow the temporal changes from 24 May 2015 to 11 July 2015. The morphological changes observed on the surface are visible in the form of roundish features, which are growing in size from a given location in a preferential direction, at a rate of 5.6 - 8.1$\times$10$^{-5}$ m s$^{-1}$ during the observational period. The location where changes started and the contours of the expanding features are bluer than the surroundings, suggesting the presence of ices (H$_2$O and/or CO$_2$) exposed on the surface. However, sublimation of ices alone is not sufficient to explain the observed expanding features. No significant variations in the dust activity pattern are observed during the period of changes. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1509.02794v1-abstract-full').style.display = 'none'; document.getElementById('1509.02794v1-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, 2015; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> September 2015. </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">4 pages, 3 figures; Letter for Astronomy and Astrophysics: accepted</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> A&A 583, A36 (2015) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1509.02707">arXiv:1509.02707</a> <span> [<a href="https://arxiv.org/pdf/1509.02707">pdf</a>, <a href="https://arxiv.org/format/1509.02707">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/10.1051/0004-6361/201526379">10.1051/0004-6361/201526379 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Gravitational slopes, geomorphology, and material strengths of the nucleus of comet 67P/Churyumov-Gerasimenko from OSIRIS observations </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Groussin%2C+O">O. Groussin</a>, <a href="/search/?searchtype=author&query=Jorda%2C+L">L. Jorda</a>, <a href="/search/?searchtype=author&query=Auger%2C+A+-">A. -T. Auger</a>, <a href="/search/?searchtype=author&query=K%C3%BChrt%2C+E">E. K眉hrt</a>, <a href="/search/?searchtype=author&query=Gaskell%2C+R">R. Gaskell</a>, <a href="/search/?searchtype=author&query=Capanna%2C+C">C. Capanna</a>, <a href="/search/?searchtype=author&query=Scholten%2C+F">F. Scholten</a>, <a href="/search/?searchtype=author&query=Preusker%2C+F">F. Preusker</a>, <a href="/search/?searchtype=author&query=Lamy%2C+P">P. Lamy</a>, <a href="/search/?searchtype=author&query=Hviid%2C+S">S. Hviid</a>, <a href="/search/?searchtype=author&query=Knollenberg%2C+J">J. Knollenberg</a>, <a href="/search/?searchtype=author&query=Keller%2C+U">U. Keller</a>, <a href="/search/?searchtype=author&query=Huettig%2C+C">C. Huettig</a>, <a href="/search/?searchtype=author&query=Sierks%2C+H">H. Sierks</a>, <a href="/search/?searchtype=author&query=Barbieri%2C+C">C. Barbieri</a>, <a href="/search/?searchtype=author&query=Rodrigo%2C+R">R. Rodrigo</a>, <a href="/search/?searchtype=author&query=Koschny%2C+D">D. Koschny</a>, <a href="/search/?searchtype=author&query=Rickman%2C+H">H. Rickman</a>, <a href="/search/?searchtype=author&query=Hearn%2C+M+F+A">M. F. A Hearn</a>, <a href="/search/?searchtype=author&query=Agarwal%2C+J">J. Agarwal</a>, <a href="/search/?searchtype=author&query=Barucci%2C+M+A">M. A. Barucci</a>, <a href="/search/?searchtype=author&query=Bertaux%2C+J+-">J. -L. Bertaux</a>, <a href="/search/?searchtype=author&query=Bertini%2C+I">I. Bertini</a>, <a href="/search/?searchtype=author&query=Boudreault%2C+S">S. Boudreault</a>, <a href="/search/?searchtype=author&query=Cremonese%2C+G">G. Cremonese</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="1509.02707v1-abstract-short" style="display: inline;"> We study the link between gravitational slopes and the surface morphology on the nucleus of comet 67P/Churyumov-Gerasimenko and provide constraints on the mechanical properties of the cometary material. We computed the gravitational slopes for five regions on the nucleus that are representative of the different morphologies observed on the surface, using two shape models computed from OSIRIS image… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1509.02707v1-abstract-full').style.display = 'inline'; document.getElementById('1509.02707v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1509.02707v1-abstract-full" style="display: none;"> We study the link between gravitational slopes and the surface morphology on the nucleus of comet 67P/Churyumov-Gerasimenko and provide constraints on the mechanical properties of the cometary material. We computed the gravitational slopes for five regions on the nucleus that are representative of the different morphologies observed on the surface, using two shape models computed from OSIRIS images by the stereo-photoclinometry (SPC) and stereo-photogrammetry (SPG) techniques. We estimated the tensile, shear, and compressive strengths using different surface morphologies and mechanical considerations. The different regions show a similar general pattern in terms of the relation between gravitational slopes and terrain morphology: i) low-slope terrains (0-20 deg) are covered by a fine material and contain a few large ($>$10 m) and isolated boulders, ii) intermediate-slope terrains (20-45 deg) are mainly fallen consolidated materials and debris fields, with numerous intermediate-size boulders from $<$1 m to 10 m for the majority of them, and iii) high-slope terrains (45-90 deg) are cliffs that expose a consolidated material and do not show boulders or fine materials. The best range for the tensile strength of overhangs is 3-15 Pa (upper limit of 150 Pa), 4-30 Pa for the shear strength of fine surface materials and boulders, and 30-150 Pa for the compressive strength of overhangs (upper limit of 1500 Pa). The strength-to-gravity ratio is similar for 67P and weak rocks on Earth. As a result of the low compressive strength, the interior of the nucleus may have been compressed sufficiently to initiate diagenesis, which could have contributed to the formation of layers. Our value for the tensile strength is comparable to that of dust aggregates formed by gravitational instability and tends to favor a formation of comets by the accrection of pebbles at low velocities. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1509.02707v1-abstract-full').style.display = 'none'; document.getElementById('1509.02707v1-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, 2015; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> September 2015. </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, 15 figures, 1 table; Astronomy and Astrophysics, 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/1505.07021">arXiv:1505.07021</a> <span> [<a href="https://arxiv.org/pdf/1505.07021">pdf</a>, <a href="https://arxiv.org/ps/1505.07021">ps</a>, <a href="https://arxiv.org/format/1505.07021">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/10.1051/0004-6361/201526093">10.1051/0004-6361/201526093 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Comet 67P/Churyumov-Gerasimenko: Constraints on its origin from OSIRIS observations </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Rickman%2C+H">H. Rickman</a>, <a href="/search/?searchtype=author&query=Marchi%2C+S">S. Marchi</a>, <a href="/search/?searchtype=author&query=A%27Hearn%2C+M+F">M. F. A'Hearn</a>, <a href="/search/?searchtype=author&query=Barbieri%2C+C">C. Barbieri</a>, <a href="/search/?searchtype=author&query=El-Maarry%2C+M+R">M. R. El-Maarry</a>, <a href="/search/?searchtype=author&query=G%C3%BCttler%2C+C">C. G眉ttler</a>, <a href="/search/?searchtype=author&query=Ip%2C+W+-">W. -H. Ip</a>, <a href="/search/?searchtype=author&query=Keller%2C+H+U">H. U. Keller</a>, <a href="/search/?searchtype=author&query=Lamy%2C+P">P. Lamy</a>, <a href="/search/?searchtype=author&query=Marzari%2C+F">F. Marzari</a>, <a href="/search/?searchtype=author&query=Massironi%2C+M">M. Massironi</a>, <a href="/search/?searchtype=author&query=Naletto%2C+G">G. Naletto</a>, <a href="/search/?searchtype=author&query=Pajola%2C+M">M. Pajola</a>, <a href="/search/?searchtype=author&query=Sierks%2C+H">H. Sierks</a>, <a href="/search/?searchtype=author&query=Team%2C+O">OSIRIS Team</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="1505.07021v1-abstract-short" style="display: inline;"> One of the main aims of the ESA Rosetta mission is to study the origin of the solar system by exploring comet 67P/Churyumov-Gerasimenko at close range. In this paper we discuss the origin and evolution of comet 67P/Churyumov-Gerasimenko in relation to that of comets in general and in the framework of current solar system formation models. We use data from the OSIRIS scientific cameras as basic con… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1505.07021v1-abstract-full').style.display = 'inline'; document.getElementById('1505.07021v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1505.07021v1-abstract-full" style="display: none;"> One of the main aims of the ESA Rosetta mission is to study the origin of the solar system by exploring comet 67P/Churyumov-Gerasimenko at close range. In this paper we discuss the origin and evolution of comet 67P/Churyumov-Gerasimenko in relation to that of comets in general and in the framework of current solar system formation models. We use data from the OSIRIS scientific cameras as basic constraints. In particular, we discuss the overall bi-lobate shape and the presence of key geological features, such as layers and fractures. We also treat the problem of collisional evolution of comet nuclei by a particle-in-a-box calculation for an estimate of the probability of survival for 67P/Churyumov-Gerasimenko during the early epochs of the solar system. We argue that the two lobes of the 67P/Churyumov-Gerasimenko nucleus are derived from two distinct objects that have formed a contact binary via a gentle merger. The lobes are separate bodies, though sufficiently similar to have formed in the same environment. An estimate of the collisional rate in the primordial, trans-planetary disk shows that most comets of similar size to 67P/Churyumov-Gerasimenko are likely collisional fragments, although survival of primordial planetesimals cannot be excluded. A collisional origin of the contact binary is suggested, and the low bulk density of the aggregate and abundance of volatile species show that a very gentle merger must have occurred. We thus consider two main scenarios: the primordial accretion of planetesimals, and the re-accretion of fragments after an energetic impact onto a larger parent body. We point to the primordial signatures exhibited by 67P/Churyumov-Gerasimenko and other comet nuclei as critical tests of the collisional evolution. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1505.07021v1-abstract-full').style.display = 'none'; document.getElementById('1505.07021v1-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 May, 2015; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> May 2015. </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, to appear on Astronomy & Astrophysics</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1505.06888">arXiv:1505.06888</a> <span> [<a href="https://arxiv.org/pdf/1505.06888">pdf</a>, <a href="https://arxiv.org/ps/1505.06888">ps</a>, <a href="https://arxiv.org/format/1505.06888">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/10.1051/0004-6361/201525901">10.1051/0004-6361/201525901 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Spectrophotometric properties of the nucleus of comet 67P/Churyumov-Gerasimenko from the OSIRIS instrument onboard the ROSETTA spacecraft </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Fornasier%2C+S">S. Fornasier</a>, <a href="/search/?searchtype=author&query=Hasselmann%2C+P+H">P. H. Hasselmann</a>, <a href="/search/?searchtype=author&query=Barucci%2C+M+A">M. A. Barucci</a>, <a href="/search/?searchtype=author&query=Feller%2C+C">C. Feller</a>, <a href="/search/?searchtype=author&query=Besse%2C+S">S. Besse</a>, <a href="/search/?searchtype=author&query=Leyrat%2C+C">C. Leyrat</a>, <a href="/search/?searchtype=author&query=Lara%2C+L">L. Lara</a>, <a href="/search/?searchtype=author&query=Gutierrez%2C+P+J">P. J. Gutierrez</a>, <a href="/search/?searchtype=author&query=Oklay%2C+N">N. Oklay</a>, <a href="/search/?searchtype=author&query=Tubiana%2C+C">C. Tubiana</a>, <a href="/search/?searchtype=author&query=Scholten%2C+F">F. Scholten</a>, <a href="/search/?searchtype=author&query=Sierks%2C+H">H. Sierks</a>, <a href="/search/?searchtype=author&query=Barbieri%2C+C">C. Barbieri</a>, <a href="/search/?searchtype=author&query=Lamy%2C+P+L">P. L. Lamy</a>, <a href="/search/?searchtype=author&query=Rodrigo%2C+R">R. Rodrigo</a>, <a href="/search/?searchtype=author&query=Koschny%2C+D">D. Koschny</a>, <a href="/search/?searchtype=author&query=Rickman%2C+H">H. Rickman</a>, <a href="/search/?searchtype=author&query=Keller%2C+H+U">H. U. Keller</a>, <a href="/search/?searchtype=author&query=Agarwal%2C+J">J. Agarwal</a>, <a href="/search/?searchtype=author&query=A%27Hearn%2C+M+F">M. F. A'Hearn</a>, <a href="/search/?searchtype=author&query=Bertaux%2C+J+-">J. -L. Bertaux</a>, <a href="/search/?searchtype=author&query=Bertini%2C+I">I. Bertini</a>, <a href="/search/?searchtype=author&query=Cremonese%2C+G">G. Cremonese</a>, <a href="/search/?searchtype=author&query=Da+Deppo%2C+V">V. Da Deppo</a>, <a href="/search/?searchtype=author&query=Davidsson%2C+B">B. Davidsson</a> , et al. (29 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="1505.06888v1-abstract-short" style="display: inline;"> The Rosetta mission of the European Space Agency has been orbiting the comet 67P/Churyumov-Gerasimenko (67P) since August 2014 and is now in its escort phase. A large complement of scientific experiments designed to complete the most detailed study of a comet ever attempted are onboard Rosetta. We present results for the photometric and spectrophotometric properties of the nucleus of 67P derived f… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1505.06888v1-abstract-full').style.display = 'inline'; document.getElementById('1505.06888v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1505.06888v1-abstract-full" style="display: none;"> The Rosetta mission of the European Space Agency has been orbiting the comet 67P/Churyumov-Gerasimenko (67P) since August 2014 and is now in its escort phase. A large complement of scientific experiments designed to complete the most detailed study of a comet ever attempted are onboard Rosetta. We present results for the photometric and spectrophotometric properties of the nucleus of 67P derived from the OSIRIS imaging system, which consists of a Wide Angle Camera (WAC) and a Narrow Angle Camera (NAC). The disk-averaged phase function of the nucleus of 67P shows a strong opposition surge with a G parameter value of -0.13$\pm$0.01 in the HG system formalism and an absolute magnitude $H_v(1,1,0)$ = 15.74$\pm$0.02 mag. The integrated spectrophotometry in 20 filters covering the 250-1000 nm wavelength range shows a red spectral behavior, without clear absorption bands except for a potential absorption centered at $\sim$ 290 nm that is possibly due to SO$_2$ ice. The nucleus shows strong phase reddening, with disk-averaged spectral slopes increasing from 11\%/(100 nm) to 16\%/(100 nm) in the 1.3$^{\circ}$--54$^{\circ}$ phase angle range. The geometric albedo of the comet is 6.5$\pm$0.2\% at 649 nm, with local variations of up to $\sim$ 16\% in the Hapi region. From the disk-resolved images we computed the spectral slope together with local spectrophotometry and identified three distinct groups of regions (blue, moderately red, and red). The Hapi region is the brightest, the bluest in term of spectral slope, and the most active surface on the comet. Local spectrophotometry shows an enhancement of the flux in the 700-750 nm that is associated with coma emissions. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1505.06888v1-abstract-full').style.display = 'none'; document.getElementById('1505.06888v1-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 May, 2015; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> May 2015. </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, 14 figures, Astronomy and Astrophysics, in press</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> A&A 583, A30 (2015) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1505.02923">arXiv:1505.02923</a> <span> [<a href="https://arxiv.org/pdf/1505.02923">pdf</a>, <a href="https://arxiv.org/format/1505.02923">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/10.1016/j.icarus.2015.04.033">10.1016/j.icarus.2015.04.033 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> The stratification of regolith on celestial objects </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Schr%C3%A4pler%2C+R">Rainer Schr盲pler</a>, <a href="/search/?searchtype=author&query=Blum%2C+J">J眉rgen Blum</a>, <a href="/search/?searchtype=author&query=von+Borstel%2C+I">Ingo von Borstel</a>, <a href="/search/?searchtype=author&query=G%C3%BCttler%2C+C">Carsten G眉ttler</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="1505.02923v2-abstract-short" style="display: inline;"> All atmosphere-less planetary bodies are covered with a dust layer, the so-called regolith, which determines the optical, mechanical and thermal properties of their surface. These properties depend on the regolith material, the size distribution of the particles it consists of, and the porosity to which these particles are packed. We performed experiments in parabolic flights to determine the grav… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1505.02923v2-abstract-full').style.display = 'inline'; document.getElementById('1505.02923v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1505.02923v2-abstract-full" style="display: none;"> All atmosphere-less planetary bodies are covered with a dust layer, the so-called regolith, which determines the optical, mechanical and thermal properties of their surface. These properties depend on the regolith material, the size distribution of the particles it consists of, and the porosity to which these particles are packed. We performed experiments in parabolic flights to determine the gravity dependency of the packing density of regolith for solid-particle sizes of 60 $渭$m and 1 mm as well as for 100-250 $渭$m-sized agglomerates of 1.5 $渭$m-sized solid grains. We utilized g-levels between 0.7 m s$^{-2}$ and 18 m s$^{-2}$ and completed our measurements with experiments under normal gravity conditions. Based on previous experimental and theoretical literature and supported by our new experiments, we developed an analytical model to calculate the regolith stratification of celestial rocky and icy bodies and estimated the mechanical yields of the regolith under the weight of an astronaut and a spacecraft resting on these objects. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1505.02923v2-abstract-full').style.display = 'none'; document.getElementById('1505.02923v2-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> 30 August, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 12 May, 2015; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> May 2015. </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, 12 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/1304.0569">arXiv:1304.0569</a> <span> [<a href="https://arxiv.org/pdf/1304.0569">pdf</a>, <a href="https://arxiv.org/format/1304.0569">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Soft Condensed Matter">cond-mat.soft</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/10.1103/PhysRevE.87.044201">10.1103/PhysRevE.87.044201 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Granular convection and the Brazil nut effect in reduced gravity </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=G%C3%BCttler%2C+C">Carsten G眉ttler</a>, <a href="/search/?searchtype=author&query=von+Borstel%2C+I">Ingo von Borstel</a>, <a href="/search/?searchtype=author&query=Schr%C3%A4pler%2C+R">Rainer Schr盲pler</a>, <a href="/search/?searchtype=author&query=Blum%2C+J">J眉rgen Blum</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="1304.0569v1-abstract-short" style="display: inline;"> We present laboratory experiments of a vertically vibrated granular medium consisting of 1 mm diameter glass beads with embedded 8 mm diameter intruder glass beads. The experiments were performed in the laboratory as well as in a parabolic flight under reduced-gravity conditions (on Martian and Lunar gravity levels). We measured the mean rise velocity of the large glass beads and present its depen… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1304.0569v1-abstract-full').style.display = 'inline'; document.getElementById('1304.0569v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1304.0569v1-abstract-full" style="display: none;"> We present laboratory experiments of a vertically vibrated granular medium consisting of 1 mm diameter glass beads with embedded 8 mm diameter intruder glass beads. The experiments were performed in the laboratory as well as in a parabolic flight under reduced-gravity conditions (on Martian and Lunar gravity levels). We measured the mean rise velocity of the large glass beads and present its dependence on the fill height of the sample containers, the excitation acceleration, and the ambient gravity level. We find that the rise velocity scales in the same manner for all three gravity regimes and roughly linearly with gravity. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1304.0569v1-abstract-full').style.display = 'none'; document.getElementById('1304.0569v1-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 April, 2013; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> April 2013. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1302.5532">arXiv:1302.5532</a> <span> [<a href="https://arxiv.org/pdf/1302.5532">pdf</a>, <a href="https://arxiv.org/format/1302.5532">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/10.1016/j.icarus.2013.02.034">10.1016/j.icarus.2013.02.034 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Free Collisions in a Microgravity Many-Particle Experiment III: The Collision Behavior of sub-Millimeter-Sized Dust Aggregates </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Kothe%2C+S">Stefan Kothe</a>, <a href="/search/?searchtype=author&query=Blum%2C+J">J眉rgen Blum</a>, <a href="/search/?searchtype=author&query=Weidling%2C+R">Ren茅 Weidling</a>, <a href="/search/?searchtype=author&query=G%C3%BCttler%2C+C">Carsten G眉ttler</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="1302.5532v2-abstract-short" style="display: inline;"> We conducted micro-gravity experiments to study the outcome of collisions between sub-mm-sized dust agglomerates consisting of 渭m-sized SiO2 monomer grains at velocities of several cm/s. Prior to the experiments, we used X-ray computer tomography (nano-CT) imaging to study the internal structure of these dust agglomerates and found no rim compaction so that their collision behavior is not governed… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1302.5532v2-abstract-full').style.display = 'inline'; document.getElementById('1302.5532v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1302.5532v2-abstract-full" style="display: none;"> We conducted micro-gravity experiments to study the outcome of collisions between sub-mm-sized dust agglomerates consisting of 渭m-sized SiO2 monomer grains at velocities of several cm/s. Prior to the experiments, we used X-ray computer tomography (nano-CT) imaging to study the internal structure of these dust agglomerates and found no rim compaction so that their collision behavior is not governed by preparation-caused artefacts. We found that collisions between these dust aggregates can lead either to sticking or to bouncing, depending mostly on the impact velocity. While previous collision models derived the transition between both regimes from contact physics, we used the available empirical data from these and earlier experiments to derive a power law relation between dust-aggregate mass and impact velocity for the threshold between the two collision outcomes. In agreement with earlier experiments, we show that the transition between both regimes is not sharp, but follows a shallower power law than predicted by previous models (G眉ttler et al. 2010). Furthermore, we find that sticking between dust aggregates can lead to the formation of larger structures. Collisions between aggregates-of-aggregates can lead to growth at higher velocities than homogeneous dust agglomerates. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1302.5532v2-abstract-full').style.display = 'none'; document.getElementById('1302.5532v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 5 March, 2013; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 22 February, 2013; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> February 2013. </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">Correction in Version 2: Page 3, Figure 1: Updated reference Seitzinger et al. 2013 Page 10: Correction of typo value b~-4/3 Page 13: Correction of reference Schr盲pler et al. 2012</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1206.5564">arXiv:1206.5564</a> <span> [<a href="https://arxiv.org/pdf/1206.5564">pdf</a>, <a href="https://arxiv.org/format/1206.5564">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/10.1016/j.icarus.2012.06.041">10.1016/j.icarus.2012.06.041 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Cratering Experiments on the Self Armoring of Coarse-Grained Granular Targets </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=G%C3%BCttler%2C+C">Carsten G眉ttler</a>, <a href="/search/?searchtype=author&query=Hirata%2C+N">Naru Hirata</a>, <a href="/search/?searchtype=author&query=Nakamura%2C+A+M">Akiko M. Nakamura</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="1206.5564v1-abstract-short" style="display: inline;"> Recently published crater statistics on the small asteroids 25143 Itokawa and 433 Eros show a significant depletion of craters below approx. 100 m in diameter. Possible mechanisms that were brought up to explain this lack of craters were seismic crater erasure and self armoring of a coarse, boulder covered asteroid surface. While seismic shaking has been studied in this context, the concept of arm… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1206.5564v1-abstract-full').style.display = 'inline'; document.getElementById('1206.5564v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1206.5564v1-abstract-full" style="display: none;"> Recently published crater statistics on the small asteroids 25143 Itokawa and 433 Eros show a significant depletion of craters below approx. 100 m in diameter. Possible mechanisms that were brought up to explain this lack of craters were seismic crater erasure and self armoring of a coarse, boulder covered asteroid surface. While seismic shaking has been studied in this context, the concept of armoring lacks a deeper inspection and an experimental ground truth. We therefore present cratering experiments of glass bead projectiles impacting into granular glass bead targets, where the grain sizes of projectile and target are in a similar range. The impact velocities are in the range of 200 to 300 m/s. We find that craters become fainter and irregular shaped as soon as the target grains are larger than the projectile sizes and that granular craters rarely form when the size ratio between projectile and target grain is around 1:10 or smaller. In that case, we observe a formation of a strength determined crater in the first struck target grain instead. We present a simple model based on the transfer of momentum from the projectile to this first target grain, which is capable to explain our results with only a single free parameter, which is moreover well determined by previous experiments. Based on estimates of typical projectile size and boulder size on Itokawa and Eros, given that our results are representative also for km/s impact velocities, armoring should play an important role for their evolution. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1206.5564v1-abstract-full').style.display = 'none'; document.getElementById('1206.5564v1-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> 24 June, 2012; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> June 2012. </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 Icaurs</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1204.0001">arXiv:1204.0001</a> <span> [<a href="https://arxiv.org/pdf/1204.0001">pdf</a>, <a href="https://arxiv.org/format/1204.0001">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Classical Physics">physics.class-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Geophysics">physics.geo-ph</span> </div> </div> <p class="title is-5 mathjax"> Normal Collisions of Spheres: A Literature Survey on Available Experiments </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=G%C3%BCttler%2C+C">Carsten G眉ttler</a>, <a href="/search/?searchtype=author&query=Hei%C3%9Felmann%2C+D">Daniel Hei脽elmann</a>, <a href="/search/?searchtype=author&query=Blum%2C+J">J眉rgen Blum</a>, <a href="/search/?searchtype=author&query=Krijt%2C+S">Sebastiaan Krijt</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="1204.0001v2-abstract-short" style="display: inline;"> The central collision between two solid spheres or the normal collision between a sphere and a plate are important to understand in detail before studying more complex particle interactions. Models exist to describe this basic problem but are not always consistent with available experiments. An interesting benchmark to compare models and experiments is the relation between the normal coefficient o… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1204.0001v2-abstract-full').style.display = 'inline'; document.getElementById('1204.0001v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1204.0001v2-abstract-full" style="display: none;"> The central collision between two solid spheres or the normal collision between a sphere and a plate are important to understand in detail before studying more complex particle interactions. Models exist to describe this basic problem but are not always consistent with available experiments. An interesting benchmark to compare models and experiments is the relation between the normal coefficient of restitution e and the incident velocity v. In order to draw a broad comparison between experiments and models (Krijt, S., G眉ttler, C., Hei脽elmann, D., Tielens, A.G.G.M., Dominik, C., Energy dissipation in head-on collisions of spheres, submitted), we provide in this article an overview on the literature describing experiments on normal collisions, preferably providing data on e(v). We will briefly summarize our expectation on this relation according to an established collision model in order to classify these experiments. We will then provide an overview on experimental techniques, which we found in the summarized articles, as well as a listing of all experiments along with a description of the main features of these. The raw data on e(v) of the listed experiments were digitized and are provided with this article. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1204.0001v2-abstract-full').style.display = 'none'; document.getElementById('1204.0001v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 28 May, 2013; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 30 March, 2012; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> April 2012. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1201.4282">arXiv:1201.4282</a> <span> [<a href="https://arxiv.org/pdf/1201.4282">pdf</a>, <a href="https://arxiv.org/ps/1201.4282">ps</a>, <a href="https://arxiv.org/format/1201.4282">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/10.1051/0004-6361/201118475">10.1051/0004-6361/201118475 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Planetesimal formation by sweep-up: How the bouncing barrier can be beneficial to growth </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Windmark%2C+F">Fredrik Windmark</a>, <a href="/search/?searchtype=author&query=Birnstiel%2C+T">Til Birnstiel</a>, <a href="/search/?searchtype=author&query=G%C3%BCttler%2C+C">Carsten G眉ttler</a>, <a href="/search/?searchtype=author&query=Blum%2C+J">J眉rgen Blum</a>, <a href="/search/?searchtype=author&query=Dullemond%2C+C+P">Cornelis P. Dullemond</a>, <a href="/search/?searchtype=author&query=Henning%2C+T">Thomas Henning</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="1201.4282v1-abstract-short" style="display: inline;"> The formation of planetesimals is often accredited to collisional sticking of dust grains. The exact process is unknown, as collisions between larger aggregates tend to lead to fragmentation or bouncing rather than sticking. Recent laboratory experiments have however made great progress in the understanding and mapping of the complex physics involved in dust collisions. We want to study the possib… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1201.4282v1-abstract-full').style.display = 'inline'; document.getElementById('1201.4282v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1201.4282v1-abstract-full" style="display: none;"> The formation of planetesimals is often accredited to collisional sticking of dust grains. The exact process is unknown, as collisions between larger aggregates tend to lead to fragmentation or bouncing rather than sticking. Recent laboratory experiments have however made great progress in the understanding and mapping of the complex physics involved in dust collisions. We want to study the possibility of planetesimal formation using the results from the latest laboratory experiments, particularly by including the fragmentation with mass transfer effect, which might lead to growth even at high impact velocities. We present a new experimentally and physically motivated dust collision model capable of predicting the outcome of a collision between two particles of arbitrary masses and velocities. It is used together with a continuum dust-size evolution code that is both fast in terms of execution time and able to resolve the dust well at all sizes, allowing for all types of interactions to be studied without biases. We find that for the general dust population, bouncing collisions prevent the growth above millimeter-sizes. However, if a small number of cm-sized particles are introduced, for example due to vertical mixing or radial drift, they can act as a catalyst and start to sweep up the smaller particles. At a distance of 3 AU, 100-meter-sized bodies are formed on a timescale of 1 Myr. We conclude that direct growth of planetesimals might be a possibility thanks to a combination of the existence of a bouncing barrier and the fragmentation with mass transfer effect. The bouncing barrier is here even beneficial, as it prevents the growth of too many large particles that would otherwise only fragment among each other, and creates a reservoir of small particles that can be swept up by larger bodies. However, for this process to work, a few seeds of cm in size or larger have to be introduced. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1201.4282v1-abstract-full').style.display = 'none'; document.getElementById('1201.4282v1-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 January, 2012; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> January 2012. </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">17 pages, 13 figures. Accepted for publication in Astronomy and Astrophysics</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1105.3909">arXiv:1105.3909</a> <span> [<a href="https://arxiv.org/pdf/1105.3909">pdf</a>, <a href="https://arxiv.org/format/1105.3909">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/10.1016/j.icarus.2012.01.012">10.1016/j.icarus.2012.01.012 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Free Collisions in a Microgravity Many-Particle Experiment. I. Dust Aggregate Sticking at Low Velocities </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Weidling%2C+R">Ren茅 Weidling</a>, <a href="/search/?searchtype=author&query=G%C3%BCttler%2C+C">Carsten G眉ttler</a>, <a href="/search/?searchtype=author&query=Blum%2C+J">J眉rgen Blum</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="1105.3909v2-abstract-short" style="display: inline;"> Over the past years the processes involved in the growth of planetesimals have extensively been studied in the laboratory. Based on these experiments, a dust-aggregate collision model was developed upon which computer simulations were based to evaluate how big protoplanetary dust aggregates can grow and to analyze which kinds of collisions are relevant in the solar nebula and are worth further stu… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1105.3909v2-abstract-full').style.display = 'inline'; document.getElementById('1105.3909v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1105.3909v2-abstract-full" style="display: none;"> Over the past years the processes involved in the growth of planetesimals have extensively been studied in the laboratory. Based on these experiments, a dust-aggregate collision model was developed upon which computer simulations were based to evaluate how big protoplanetary dust aggregates can grow and to analyze which kinds of collisions are relevant in the solar nebula and are worth further studies in the laboratory. The sticking threshold velocity of millimeter-sized dust aggregates is such a critical value that had so far only theoretically been derived, as the relevant velocities could not be reached in the laboratory. We developed a microgravity experiment that allows us for the first time to study free collisions of mm-sized dust aggregates down to velocities of ~0.1 cm/s to assess this part of the protoplanetary dust evolution model. Here, we present the results of 125 free collisions between dust aggregates of 0.5 to 2 mm diameter. Seven collisions with velocities between 0.2 and 3 cm/s led to sticking, suggesting a transition from perfect sticking to perfect bouncing with a certain sticking probability instead of a sharp velocity threshold. We developed a model to explain the physical processes involved in dust-aggregate sticking, derived dynamic material properties of the dust aggregates from the results of the collisions, and deduced the velocity below which aggregates always stick. For millimeter-sized porous dust aggregates this velocity is 8e-5 m/s. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1105.3909v2-abstract-full').style.display = 'none'; document.getElementById('1105.3909v2-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 October, 2011; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 19 May, 2011; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> May 2011. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">accepted by Icarus</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1105.3897">arXiv:1105.3897</a> <span> [<a href="https://arxiv.org/pdf/1105.3897">pdf</a>, <a href="https://arxiv.org/format/1105.3897">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/10.1016/j.icarus.2011.11.036">10.1016/j.icarus.2011.11.036 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Free Collisions in a Microgravity Many-Particle Experiment. II. The Collision Dynamics of Dust-Coated Chondrules </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Beitz%2C+E">Eike Beitz</a>, <a href="/search/?searchtype=author&query=G%C3%BCttler%2C+C">Carsten G眉ttler</a>, <a href="/search/?searchtype=author&query=Weidling%2C+R">Ren茅 Weidling</a>, <a href="/search/?searchtype=author&query=Blum%2C+J">J眉rgen Blum</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="1105.3897v2-abstract-short" style="display: inline;"> The formation of planetesimals in the early Solar System is hardly understood, and in particular the growth of dust aggregates above millimeter sizes has recently turned out to be a difficult task in our understanding [Zsom et al. 2010, A&A, 513, A57]. Laboratory experiments have shown that dust aggregates of these sizes stick to one another only at unreasonably low velocities. However, in the pro… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1105.3897v2-abstract-full').style.display = 'inline'; document.getElementById('1105.3897v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1105.3897v2-abstract-full" style="display: none;"> The formation of planetesimals in the early Solar System is hardly understood, and in particular the growth of dust aggregates above millimeter sizes has recently turned out to be a difficult task in our understanding [Zsom et al. 2010, A&A, 513, A57]. Laboratory experiments have shown that dust aggregates of these sizes stick to one another only at unreasonably low velocities. However, in the protoplanetary disk, millimeter-sized particles are known to have been ubiquitous. One can find relics of them in the form of solid chondrules as the main constituent of chondrites. Most of these chondrules were found to feature a fine-grained rim, which is hypothesized to have formed from accreting dust grains in the solar nebula. To study the influence of these dust-coated chondrules on the formation of chondrites and possibly planetesimals, we conducted collision experiments between millimeter-sized, dust-coated chondrule analogs at velocities of a few cm/s. For 2 and 3 mm diameter chondrule analogs covered by dusty rims of a volume filling factor of 0.18 and 0.35-0.58, we found sticking velocities of a few cm/s. This velocity is higher than the sticking velocity of dust aggregates of the same size. We therefore conclude that chondrules may be an important step towards a deeper understanding of the collisional growth of larger bodies. Moreover, we analyzed the collision behavior in an ensemble of dust aggregates and non-coated chondrule analogs. While neither the dust aggregates nor the solid chondrule analogs show sticking in collisions among their species, we found an enhanced sicking efficiency in collisions between the two constituents, which leads us to the conjecture that chondrules might act as "catalyzers" for the growth of larger bodies in the young Solar System. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1105.3897v2-abstract-full').style.display = 'none'; document.getElementById('1105.3897v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 5 December, 2011; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 19 May, 2011; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> May 2011. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1102.4441">arXiv:1102.4441</a> <span> [<a href="https://arxiv.org/pdf/1102.4441">pdf</a>, <a href="https://arxiv.org/format/1102.4441">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/10.1088/0004-637X/736/1/34">10.1088/0004-637X/736/1/34 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Low-velocity collisions of centimeter-sized dust aggregates </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Beitz%2C+E">Eike Beitz</a>, <a href="/search/?searchtype=author&query=G%C3%BCttler%2C+C">Carsten G眉ttler</a>, <a href="/search/?searchtype=author&query=Blum%2C+J">J眉rgen Blum</a>, <a href="/search/?searchtype=author&query=Meisner%2C+T">Thorsten Meisner</a>, <a href="/search/?searchtype=author&query=Teiser%2C+J">Jens Teiser</a>, <a href="/search/?searchtype=author&query=Wurm%2C+G">Gerhard Wurm</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="1102.4441v3-abstract-short" style="display: inline;"> Collisions between centimeter- to decimeter-sized dusty bodies are important to understand the mechanisms leading to the formation of planetesimals. We thus performed laboratory experiments to study the collisional behavior of dust aggregates in this size range at velocities below and around the fragmentation threshold. We developed two independent experimental setups with the same goal to study t… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1102.4441v3-abstract-full').style.display = 'inline'; document.getElementById('1102.4441v3-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1102.4441v3-abstract-full" style="display: none;"> Collisions between centimeter- to decimeter-sized dusty bodies are important to understand the mechanisms leading to the formation of planetesimals. We thus performed laboratory experiments to study the collisional behavior of dust aggregates in this size range at velocities below and around the fragmentation threshold. We developed two independent experimental setups with the same goal to study the effects of bouncing, fragmentation, and mass transfer in free particle-particle collisions. The first setup is an evacuated drop tower with a free-fall height of 1.5 m, providing us with 0.56 s of microgravity time so that we observed collisions with velocities between 8 mm/s and 2 m/s. The second setup is designed to study the effect of partial fragmentation (when only one of the two aggregates is destroyed) and mass transfer in more detail. It allows for the measurement of the accretion efficiency as the samples are safely recovered after the encounter. Our results are that for very low velocities we found bouncing as could be expected while the fragmentation velocity of 20 cm/s was significantly lower than expected. We present the critical energy for disruptive collisions Q*, which showed up to be at least two orders of magnitude lower than previous experiments in the literature. In the wide range between bouncing and disruptive collisions, only one of the samples fragmented in the encounter while the other gained mass. The accretion efficiency in the order of a few percent of the particle's mass is depending on the impact velocity and the sample porosity. Our results will have consequences for dust evolution models in protoplanetary disks as well as for the strength of large, porous planetesimal bodies. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1102.4441v3-abstract-full').style.display = 'none'; document.getElementById('1102.4441v3-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 May, 2011; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 22 February, 2011; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> February 2011. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1009.4341">arXiv:1009.4341</a> <span> [<a href="https://arxiv.org/pdf/1009.4341">pdf</a>, <a href="https://arxiv.org/format/1009.4341">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/10.1088/0004-637X/725/1/1242">10.1088/0004-637X/725/1/1242 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> The Physics of Protoplanetesimal Dust Agglomerates. V. Multiple Impacts of Dusty Agglomerates at Velocities Above the Fragmentation Threshold </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Kothe%2C+S">Stefan Kothe</a>, <a href="/search/?searchtype=author&query=G%C3%BCttler%2C+C">Carsten G眉ttler</a>, <a href="/search/?searchtype=author&query=Blum%2C+J">J眉rgen Blum</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="1009.4341v1-abstract-short" style="display: inline;"> In the last years, experiments have shown that collisions above the fragmentation threshold velocity are a potentially important growth process for protoplanatary dust aggregates. To obtain deeper understanding of this process, we performed laboratory and drop-tower experiments to study multiple impacts of small, porous dust-aggregate projectiles onto sintered dust targets. Projectile and target c… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1009.4341v1-abstract-full').style.display = 'inline'; document.getElementById('1009.4341v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1009.4341v1-abstract-full" style="display: none;"> In the last years, experiments have shown that collisions above the fragmentation threshold velocity are a potentially important growth process for protoplanatary dust aggregates. To obtain deeper understanding of this process, we performed laboratory and drop-tower experiments to study multiple impacts of small, porous dust-aggregate projectiles onto sintered dust targets. Projectile and target consisted of 1.5 micron monodisperse, spherical SiO2 monomers with volume filling factors of 0.15 (projectiles) and 0.45 (targets). The projectiles were accelerated by a solenoid magnet and combined with a magazine with which 25 impacts onto the same spot on the target could be performed in vacuum. We measured the mass-accretion efficiency and the volume filling factor for different impact velocities between 1.5 and 6.0 m/s. The experiments at the lowest impact speeds were performed in the Bremen drop-tower under microgravity conditions. Within this velocity range we found a linear increase of the accretion efficiency with increasing velocity. In the laboratory experiments, the accretion efficiency increases from 0.12 to 0.21 in units of the projectile mass. The recorded images of the impacts showed that the mass transfer from the projectile to the target leads to the growth of a conical structure on the target. From the images we also measured the volume filling factors of the grown structures, which ranged from 0.15 (uncompacted) to 0.40 (significantly compacted) with increasing impact speed. These results augment our knowledge of the aggregate growth in protoplanetary disks and should be taken into account for future models of protoplanetary dust growth. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1009.4341v1-abstract-full').style.display = 'none'; document.getElementById('1009.4341v1-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 September, 2010; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> September 2010. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">accepted by 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/1001.1617">arXiv:1001.1617</a> <span> [<a href="https://arxiv.org/pdf/1001.1617">pdf</a>, <a href="https://arxiv.org/ps/1001.1617">ps</a>, <a href="https://arxiv.org/format/1001.1617">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/10.1051/0004-6361/200913596">10.1051/0004-6361/200913596 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Numerical Simulations of Highly Porous Dust Aggregates in the Low-Velocity Collision Regime </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Geretshauser%2C+R+J">Ralf J. Geretshauser</a>, <a href="/search/?searchtype=author&query=Speith%2C+R">Roland Speith</a>, <a href="/search/?searchtype=author&query=G%C3%BCttler%2C+C">Carsten G眉ttler</a>, <a href="/search/?searchtype=author&query=Krause%2C+M">Maya Krause</a>, <a href="/search/?searchtype=author&query=Blum%2C+J">J眉rgen Blum</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="1001.1617v1-abstract-short" style="display: inline;"> A highly favoured mechanism of planetesimal formation is collisional growth. Single dust grains, which follow gas flows in the protoplanetary disc, hit each other, stick due to van der Waals forces and form fluffy aggregates up to centimetre size. The mechanism of further growth is unclear since the outcome of aggregate collisions in the relevant velocity and size regime cannot be investigated i… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1001.1617v1-abstract-full').style.display = 'inline'; document.getElementById('1001.1617v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1001.1617v1-abstract-full" style="display: none;"> A highly favoured mechanism of planetesimal formation is collisional growth. Single dust grains, which follow gas flows in the protoplanetary disc, hit each other, stick due to van der Waals forces and form fluffy aggregates up to centimetre size. The mechanism of further growth is unclear since the outcome of aggregate collisions in the relevant velocity and size regime cannot be investigated in the laboratory under protoplanetary disc conditions. Realistic statistics of the result of dust aggregate collisions beyond decimetre size is missing for a deeper understanding of planetary growth. Joining experimental and numerical efforts we want to calibrate and validate a computer program that is capable of a correct simulation of the macroscopic behaviour of highly porous dust aggregates. After testing its numerical limitations thoroughly we will check the program especially for a realistic reproduction of various benchmark experiments. We adopt the smooth particle hydrodynamics (SPH) numerical scheme with extensions for the simulation of solid bodies and a modified version of the Sirono porosity model. Experimentally measured macroscopic material properties of silica dust are implemented. We calibrate and test for the compressive strength relation and the bulk modulus. SPH has already proven to be a suitable tool to simulate collisions at rather high velocities. In this work we demonstrate that its area of application can not only be extended to low-velocity experiments and collisions. It can also be used to simulate the behaviour of highly porous objects in this velocity regime to a very high accuracy.The result of the calibration process in this work is an SPH code that can be utilised to investigate the collisional outcome of porous dust in the low-velocity regime. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1001.1617v1-abstract-full').style.display = 'none'; document.getElementById('1001.1617v1-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 January, 2010; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> January 2010. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">accepted by Astronomy & Astrophysics</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1001.0488">arXiv:1001.0488</a> <span> [<a href="https://arxiv.org/pdf/1001.0488">pdf</a>, <a href="https://arxiv.org/ps/1001.0488">ps</a>, <a href="https://arxiv.org/format/1001.0488">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/10.1051/0004-6361/200912976">10.1051/0004-6361/200912976 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> The outcome of protoplanetary dust growth: pebbles, boulders, or planetesimals? II. Introducing the bouncing barrier </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Zsom%2C+A">A. Zsom</a>, <a href="/search/?searchtype=author&query=Ormel%2C+C+W">C. W. Ormel</a>, <a href="/search/?searchtype=author&query=Guettler%2C+C">C. Guettler</a>, <a href="/search/?searchtype=author&query=Blum%2C+J">J. Blum</a>, <a href="/search/?searchtype=author&query=Dullemond%2C+C+P">C. P. Dullemond</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="1001.0488v1-abstract-short" style="display: inline;"> The sticking of micron sized dust particles due to surface forces in circumstellar disks is the first stage in the production of asteroids and planets. The key ingredients that drive this process are the relative velocity between the dust particles in this environment and the complex physics of dust aggregate collisions. Here we present the results of a collision model, which is based on laborat… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1001.0488v1-abstract-full').style.display = 'inline'; document.getElementById('1001.0488v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1001.0488v1-abstract-full" style="display: none;"> The sticking of micron sized dust particles due to surface forces in circumstellar disks is the first stage in the production of asteroids and planets. The key ingredients that drive this process are the relative velocity between the dust particles in this environment and the complex physics of dust aggregate collisions. Here we present the results of a collision model, which is based on laboratory experiments of these aggregates. We investigate the maximum aggregate size and mass that can be reached by coagulation in protoplanetary disks. We model the growth of dust aggregates at 1 AU at the midplane at three different gas densities. We find that the evolution of the dust does not follow the previously assumed growth-fragmentation cycles. Catastrophic fragmentation hardly occurs in the three disk models. Furthermore we see long lived, quasi-steady states in the distribution function of the aggregates due to bouncing. We explore how the mass and the porosity change upon varying the turbulence parameter and by varying the critical mass ratio of dust particles. Particles reach Stokes numbers of roughly 10^-4 during the simulations. The particle growth is stopped by bouncing rather than fragmentation in these models. The final Stokes number of the aggregates is rather insensitive to the variations of the gas density and the strength of turbulence. The maximum mass of the particles is limited to approximately 1 gram (chondrule-sized particles). Planetesimal formation can proceed via the turbulent concentration of these aerodynamically size-sorted chondrule-sized particles. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1001.0488v1-abstract-full').style.display = 'none'; document.getElementById('1001.0488v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 4 January, 2010; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> January 2010. </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/0910.4251">arXiv:0910.4251</a> <span> [<a href="https://arxiv.org/pdf/0910.4251">pdf</a>, <a href="https://arxiv.org/format/0910.4251">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/10.1051/0004-6361/200912852">10.1051/0004-6361/200912852 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> The outcome of protoplanetary dust growth: pebbles, boulders, or planetesimals? I. Mapping the zoo of laboratory collision experiments </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=G%C3%BCttler%2C+C">Carsten G眉ttler</a>, <a href="/search/?searchtype=author&query=Blum%2C+J">J眉rgen Blum</a>, <a href="/search/?searchtype=author&query=Zsom%2C+A">Andras Zsom</a>, <a href="/search/?searchtype=author&query=Ormel%2C+C+W">Chris W. Ormel</a>, <a href="/search/?searchtype=author&query=Dullemond%2C+C+P">Cornelis P. Dullemond</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="0910.4251v2-abstract-short" style="display: inline;"> The growth processes from protoplanetary dust to planetesimals are not fully understood. Laboratory experiments and theoretical models have shown that collisions among the dust aggregates can lead to sticking, bouncing, and fragmentation. However, no systematic study on the collisional outcome of protoplanetary dust has been performed so far so that a physical model of the dust evolution in prot… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('0910.4251v2-abstract-full').style.display = 'inline'; document.getElementById('0910.4251v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="0910.4251v2-abstract-full" style="display: none;"> The growth processes from protoplanetary dust to planetesimals are not fully understood. Laboratory experiments and theoretical models have shown that collisions among the dust aggregates can lead to sticking, bouncing, and fragmentation. However, no systematic study on the collisional outcome of protoplanetary dust has been performed so far so that a physical model of the dust evolution in protoplanetary disks is still missing. We intend to map the parameter space for the collisional interaction of arbitrarily porous dust aggregates. This parameter space encompasses the dust-aggregate masses, their porosities and the collision velocity. With such a complete mapping of the collisional outcomes of protoplanetary dust aggregates, it will be possible to follow the collisional evolution of dust in a protoplanetary disk environment. We use literature data, perform own laboratory experiments, and apply simple physical models to get a complete picture of the collisional interaction of protoplanetary dust aggregates. In our study, we found four different types of sticking, two types of bouncing, and three types of fragmentation as possible outcomes in collisions among protoplanetary dust aggregates. We distinguish between eight combinations of porosity and mass ratio. For each of these cases, we present a complete collision model for dust-aggregate masses between 10^-12 and 10^2 g and collision velocities in the range 10^-4 to 10^4 cm/s for arbitrary porosities. This model comprises the collisional outcome, the mass(es) of the resulting aggregate(s) and their porosities. We present the first complete collision model for protoplanetary dust. This collision model can be used for the determination of the dust-growth rate in protoplanetary disks. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('0910.4251v2-abstract-full').style.display = 'none'; document.getElementById('0910.4251v2-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 November, 2009; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 22 October, 2009; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> October 2009. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">accepted by Astronomy and Astrophysics</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/0906.0088">arXiv:0906.0088</a> <span> [<a href="https://arxiv.org/pdf/0906.0088">pdf</a>, <a href="https://arxiv.org/ps/0906.0088">ps</a>, <a href="https://arxiv.org/format/0906.0088">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/10.1088/0004-637X/701/1/130">10.1088/0004-637X/701/1/130 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> The Physics of Protoplanetesimal Dust Agglomerates. IV. Towards a Dynamical Collision Model </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=G%C3%BCttler%2C+C">Carsten G眉ttler</a>, <a href="/search/?searchtype=author&query=Krause%2C+M">Maya Krause</a>, <a href="/search/?searchtype=author&query=Geretshauser%2C+R+J">Ralf J. Geretshauser</a>, <a href="/search/?searchtype=author&query=Speith%2C+R">Roland Speith</a>, <a href="/search/?searchtype=author&query=Blum%2C+J">J眉rgen Blum</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="0906.0088v1-abstract-short" style="display: inline;"> Recent years have shown many advances in our knowledge of the collisional evolution of protoplanetary dust. Based on a variety of dust-collision experiments in the laboratory, our view of the growth of dust aggregates in protoplanetary disks is now supported by a deeper understanding of the physics involved in the interaction between dust agglomerates. However, the parameter space, which determi… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('0906.0088v1-abstract-full').style.display = 'inline'; document.getElementById('0906.0088v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="0906.0088v1-abstract-full" style="display: none;"> Recent years have shown many advances in our knowledge of the collisional evolution of protoplanetary dust. Based on a variety of dust-collision experiments in the laboratory, our view of the growth of dust aggregates in protoplanetary disks is now supported by a deeper understanding of the physics involved in the interaction between dust agglomerates. However, the parameter space, which determines the collisional outcome, is huge and sometimes inaccessible to laboratory experiments. Very large or fluffy dust aggregates and extremely low collision velocities are beyond the boundary of today's laboratories. It is therefore desirable to augment our empirical knowledge of dust-collision physics with a numerical method to treat arbitrary aggregate sizes, porosities and collision velocities. In this article, we implement experimentally-determined material parameters of highly porous dust aggregates into a Smooth Particle Hydrodynamics (SPH) code, in particular an omnidirectional compressive-strength and a tensile-strength relation. We also give a prescription of calibrating the SPH code with compression and low-velocity impact experiments. In the process of calibration, we developed a dynamic compressive-strength relation and estimated a relation for the shear strength. Finally, we defined and performed a series of benchmark tests and found the agreement between experimental results and numerical simulations to be very satisfactory. SPH codes have been used in the past to study collisions at rather high velocities. At the end of this work, we show examples of future applications in the low-velocity regime of collisional evolution. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('0906.0088v1-abstract-full').style.display = 'none'; document.getElementById('0906.0088v1-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> 30 May, 2009; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> June 2009. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">accepted by The astrophysical Journal</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Astrophys.J.701:130-141,2009 </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/0904.4536">arXiv:0904.4536</a> <span> [<a href="https://arxiv.org/pdf/0904.4536">pdf</a>, <a href="https://arxiv.org/ps/0904.4536">ps</a>, <a href="https://arxiv.org/format/0904.4536">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/10.1063/1.3180086">10.1063/1.3180086 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Towards a Dynamical Collision Model of Highly Porous Dust Aggregates </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=G%C3%BCttler%2C+C">Carsten G眉ttler</a>, <a href="/search/?searchtype=author&query=Krause%2C+M">Maya Krause</a>, <a href="/search/?searchtype=author&query=Geretshauser%2C+R+J">Ralf J. Geretshauser</a>, <a href="/search/?searchtype=author&query=Speith%2C+R">Roland Speith</a>, <a href="/search/?searchtype=author&query=Blum%2C+J">J眉rgen Blum</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="0904.4536v1-abstract-short" style="display: inline;"> In the recent years we have performed various experiments on the collision dynamics of highly porous dust aggregates and although we now have a comprehensive picture of the micromechanics of those aggregates, the macroscopic understanding is still lacking. We are therefore developing a mechanical model to describe dust aggregate collisions with macroscopic parameters like tensile strength, compr… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('0904.4536v1-abstract-full').style.display = 'inline'; document.getElementById('0904.4536v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="0904.4536v1-abstract-full" style="display: none;"> In the recent years we have performed various experiments on the collision dynamics of highly porous dust aggregates and although we now have a comprehensive picture of the micromechanics of those aggregates, the macroscopic understanding is still lacking. We are therefore developing a mechanical model to describe dust aggregate collisions with macroscopic parameters like tensile strength, compressive strength and shear strength. For one well defined dust sample material, the tensile and compressive strength were measured in a static experiment and implemented in a Smoothed Particle Hydrodynamics (SPH) code. A laboratory experiment was designed to compare the laboratory results with the results of the SPH simulation. In this experiment, a mm-sized glass bead is dropped into a cm-sized dust aggregate with the previously measured strength parameters. We determine the deceleration of the glass bead by high-speed imaging and the compression of the dust aggregate by x-ray micro-tomography. The measured penetration depth, stopping time and compaction under the glass bead are utilized to calibrate and test the SPH code. We find that the statically measured compressive strength curve is only applicable if we adjust it to the dynamic situation with a 'softness' parameter. After determining this parameter, the SPH code is capable of reproducing experimental results, which have not been used for the calibration before. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('0904.4536v1-abstract-full').style.display = 'none'; document.getElementById('0904.4536v1-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 April, 2009; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> April 2009. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">Accepted by "Proc. Powders and Grains 2009", Publisher AIP</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/0902.3082">arXiv:0902.3082</a> <span> [<a href="https://arxiv.org/pdf/0902.3082">pdf</a>, <a href="https://arxiv.org/format/0902.3082">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/10.1088/0004-637X/696/2/2036">10.1088/0004-637X/696/2/2036 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> The Physics of Protoplanetesimal Dust Agglomerates. III. Compaction in Multiple Collisions </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Weidling%2C+R">Ren茅 Weidling</a>, <a href="/search/?searchtype=author&query=G%C3%BCttler%2C+C">Carsten G眉ttler</a>, <a href="/search/?searchtype=author&query=Blum%2C+J">J眉rgen Blum</a>, <a href="/search/?searchtype=author&query=Brauer%2C+F">Frithjof Brauer</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="0902.3082v1-abstract-short" style="display: inline;"> To study the evolution of protoplanetary dust aggregates, we performed experiments with up to 2600 collisions between single, highly-porous dust aggregates and a solid plate. The dust aggregates consisted of spherical SiO$_2$ grains with 1.5$渭$m diameter and had an initial volume filling factor (the volume fraction of material) of $蠁_0=0.15$. The aggregates were put onto a vibrating baseplate an… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('0902.3082v1-abstract-full').style.display = 'inline'; document.getElementById('0902.3082v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="0902.3082v1-abstract-full" style="display: none;"> To study the evolution of protoplanetary dust aggregates, we performed experiments with up to 2600 collisions between single, highly-porous dust aggregates and a solid plate. The dust aggregates consisted of spherical SiO$_2$ grains with 1.5$渭$m diameter and had an initial volume filling factor (the volume fraction of material) of $蠁_0=0.15$. The aggregates were put onto a vibrating baseplate and, thus, performed multiple collisions with the plate at a mean velocity of 0.2 m s$^{-1}$. The dust aggregates were observed by a high-speed camera to measure their size which apparently decreased over time as a measure for their compaction. After 1000 collisions the volume filling factor was increased by a factor of two, while after $\sim2000$ collisions it converged to an equilibrium of $蠁\approx0.36$. In few experiments the aggregate fragmented, although the collision velocity was well below the canonical fragmentation threshold of $\sim1$ m s$^{-1}$. The compaction of the aggregate has an influence on the surface-to-mass ratio and thereby the dynamic behavior and relative velocities of dust aggregates in the protoplanetary nebula. Moreover, macroscopic material parameters, namely the tensile strength, shear strength, and compressive strength, are altered by the compaction of the aggregates, which has an influence on their further collisional behavior. The occurrence of fragmentation requires a reassessment of the fragmentation threshold velocity. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('0902.3082v1-abstract-full').style.display = 'none'; document.getElementById('0902.3082v1-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 February, 2009; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> February 2009. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">accepted by the Astrophysical Journal</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Astrophys.J.696:2036-2043,2009 </p> </li> </ol> <nav class="pagination is-small is-centered breathe-horizontal" role="navigation" 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