Athor asteroid family as the source of the EL enstatite meteorites

1C. Avdellidou (Χ. Αβδελλίδου),1M. Delbo,1A. Morbidelli,2K. J. Walsh,1,3E. Munaibari,4J. Bourdelle de Micas,5M. Devogèle,4,6S. Fornasier,7M. Gounelle,8G. van Belle
Astronomy & Astrophysics 665, L9 Open Access Link to Article [DOI https://doi.org/10.1051/0004-6361/202244590]
1Université Côte d’Azur, CNRS – Lagrange, Observatoire de la Côte d’Azur, CS 34229, 06304 Nice Cedex 4, France
2Southwest Research Institute, 1050 Walnut St. Suite 300, Boulder, CO 80302, USA
3Université Côte d’Azur, CNRS – Géoazur, Observatoire de la Côte d’Azur, 250 rue Albert Einstein, Sophia Antipolis, 06560 Valbonne, France
4LESIA, Université Paris Cité, Observatoire de Paris, Université PSL, Sorbonne Université, CNRS, 92190 Meudon, France
5Arecibo Observatory, University of Central Florida, HC-3 Box 53995 Arecibo, PR 00612, USA
6Institut Universitaire de France (IUF), 1 rue Descartes, 75231 Paris Cedex 05, France
7Muséum National d’Histoire Naturelle, Sorbonne Universités, CNRS, IMPMC – UMR CNRS 7590, 57 rue Cuvier, 75005 Paris, France
8Lowell Observatory, 1400 West Mars Hill Road, Flagstaff, AZ 86001, USA
Reproduced with permission (C)ESO

The identification of meteorite parent bodies provides the context for understanding planetesimal formation and evolution as well as the key Solar System events they have witnessed. However, identifying such links has proven challenging and some appear ambiguous. Here, we identify that the family of asteroid fragments whose largest member is (161) Athor is the unique source of the rare EL enstatite chondrite meteorites, the closest meteorites to Earth in terms of their isotopic ratios. The Athor family was created by the collisional fragmentation of a parent body 3 Gyr ago in the inner main belt. We calculate that the diameter of the Athor family progenitor was 64 km in diameter, much smaller than the putative size of the EL original planetesimal. Therefore, we deduce that the EL planetesimal that accreted in the terrestrial planet region underwent a first catastrophic collision in that region, and one of its fragments suffered a more recent catastrophic collision in the main belt, generating the current source of the EL meteorites.

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