Two independent and primitive envelopes of the bilobate nucleus of comet 67P

Massironi, M. and Simioni, E. and Marzari, F. and Cremonese, G. and Giacomini, L. and Pajola, M. and Jorda, L. and Naletto, G. and Lowry, S. and El-Maarry, Mohamed Ramy and Preusker, F. and Scholten, F. and Sierks, H. and Barbieri, C. and Lamy, P. and Rodrigo, R. and Koschny, D. and Rickman, H. and Keller, H.U. and A’Hearn, M.F. and Agarwal, J. and Auger, A.-T. and Barucci, M.A. and Bertaux, J.-L. and Bertini, I. and Besse, S. and Bodewits, D. and Capanna, C. and Da Deppo, V. and Davidsson, B. and Debei, S. and De Cecco, M. and Ferri, F. and Fornasier, S. and Fulle, M. and Gaskell, R. and Groussin, O. and Gutiérrez, P.J. and Güttler, C. and Hviid, S.F. and Ip, W.-H. and Knollenberg, J. and Kovacs, G. and Kramm, R. and Kührt, E. and Küppers, M. and La Forgia, F. and Lara, L.M. and Lazzarin, M. and Lin, Z.-Y. and Lopez Moreno, J.J. and Magrin, S. and Michalik, H. and Mottola, S. and Oklay, N. and Pommerol, A. and Thomas, N. and Tubiana, C. and Vincent, J.-B. (2015) Two independent and primitive envelopes of the bilobate nucleus of comet 67P. Nature 526 (7573), pp. 402-405. ISSN 0028-0836.

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Official URL: https://doi.org/10.1038/nature15511

Abstract

The factors shaping cometary nuclei are still largely unknown, but could be the result of concurrent effects of evolutionary1,2 and primordial processes3,4. The peculiar bilobed shape of comet 67P/Churyumov–Gerasimenko may be the result of the fusion of two objects that were once separate or the result of a localized excavation by outgassing at the interface between the two lobes5. Here we report that the comet’s major lobe is enveloped by a nearly continuous set of strata, up to 650 metres thick, which are independent of an analogous stratified envelope on the minor lobe. Gravity vectors computed for the two lobes separately are closer to perpendicular to the strata than those calculated for the entire nucleus and adjacent to the neck separating the two lobes. Therefore comet 67P/Churyumov–Gerasimenko is an accreted body of two distinct objects with ‘onion-like’ stratification, which formed before they merged. We conclude that gentle, low-velocity collisions occurred between two fully formed kilometre-sized cometesimals in the early stages of the Solar System. The notable structural similarities between the two lobes of comet 67P/Churyumov–Gerasimenko indicate that the early-forming cometesimals experienced similar primordial stratified accretion, even though they formed independently.

Metadata

Item Type:	Article
School:	Birkbeck Faculties and Schools > Faculty of Science > School of Natural Sciences
Depositing User:	Administrator
Date Deposited:	09 Nov 2018 15:46
Last Modified:	02 Aug 2023 17:46
URI:	https://eprints.bbk.ac.uk/id/eprint/25030

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