Noble gases in Dome C micrometeorites - An attempt to disentangle asteroidal and cometary sources

• Published in: Icarus
• Main Authors: Baecker, Bastian, Ott, Ulrich, Trieloff, Mario, Engrand, Cécile, Duprat, Jean
• Other Authors: Max-Planck-Institut für Chemie (MPIC), Max-Planck-Gesellschaft, Institut für Geowissenschaften Heidelberg, Universität Heidelberg Heidelberg = Heidelberg University, MTA Atomki, Partenaires INRAE, Laboratoire de Physique des 2 Infinis Irène Joliot-Curie (IJCLab), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Cosmochimie IMPMC (IMPMC_COSMO), Institut de minéralogie, de physique des matériaux et de cosmochimie (IMPMC), Muséum national d'Histoire naturelle (MNHN)-Institut de recherche pour le développement IRD : UR206-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Muséum national d'Histoire naturelle (MNHN)-Institut de recherche pour le développement IRD : UR206-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), B.B., U.O. and M.T. acknowledge funding by the German Research Foundation, DFG-grants OT 171/5-1 and 5-2, M.T. also thanks the Klaus Tschira Stiftung. Region Ile de France (DIM-ACAV+), PNP/INSU, CNES, IN2P3.Collection of the micrometeorites was performed at CONCORDIA Station (project #1120) and financially supported by the French Polar Institute (IPEV)., ANR-18-CE31-0011,COMETOR,Origine de la poussière cométaire(2018), ANR-10-LABX-0038,P2IO,Physics of the 2 infinities and the origins(2010)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2022
• Subjects: Falkensee; Germany; Micrometeorites; Noble gases; Cosmic ray exposure; Comets; Asteroids; Xenon; [SDU]Sciences of the Universe [physics]; Antarc*; Antarctic
• Online Access: https://hal.science/hal-03854561; https://hal.science/hal-03854561/document; https://hal.science/hal-03854561/file/MMs-DC-rev27-12-21.pdf; https://doi.org/10.1016/j.icarus.2022.114884

International audience We have performed a comprehensive noble gas study, including the isotopes of krypton and xenon, on a set of micrometeorites (MMs) collected from surface snow at Dome C (DC) on the Antarctic plateau. He and Ne are generally dominated by a solar component, with lower 4 He concentrations and 4 He/ 20 Ne ratios in crystalline (Xtal) compared to fine-grained carbonaceous (FgC) MMs. Concentrations of (surface-correlated) solar wind (SW) He and Ne in FgC MMs are at the high end of what has been seen in earlier work, whereas the abundances of (volume-correlated) Kr and Xe are similar to what has been found in previous studies of MMs. In most samples, isotopic ratios for Kr and Xe are in the usual range of Q-Kr and-Xe (the Q component is the dominating component in primitive macroscopic meteorites) and air. When quantifiable, cosmic ray exposure (CRE) ages based on cosmogenic 21 Ne and 3 He, in combination with the Poynting-Robertson effect, are broadly consistent with an origin of the MMs from the asteroid belt. An exception is an Xtal MM, which exhibits a cosmogenic 21 Ne concentration in agreement with an origin from beyond Saturn, consistent with a possible cometary origin. In addition, data for trapped noble gases in three (out of ten analyzed) DC MMs provide hints that these may be related to a cometary source. One sample, a fragment of a FgC MM, is of particular interest. This fragment exhibits a Xe composition, although with large analytical uncertainties, deficient in the heavy isotopes 134 Xe and 136 Xe. This is similar to the Xe isotopic pattern, probably related to cometary ice, measured by Rosetta in the coma of comet 67P/Churyumov-Gerasimenko. The same MM also has an unusually high 36 Ar/ 38 Ar ratio, consistent with Rosetta's Ar measurement (in this case the latter having a large uncertainty). The other hints are for two MMs, of crystalline (Xtal) type, that show Ne similar to that found in laboratory analysis of refractory grains captured from comet 81P/Wild 2 by the Stardust ...