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

Matteo Massironi 1, 2 Emanuele Simioni 3 Francesco Marzari 4 Gabriele Cremonese 5 Lorenza Giacomini 2 Maurizio Pajola 1 Laurent Jorda 6 Giampiero Naletto 1, 7, 3 Stephen Lowry 8 Mohamed Ramy El-Maarry 9 Frank Preusker 10 Frank Scholten 10 Holger Sierks 11 Cesare Barbieri 4 Philippe Lamy 6 Rafael Rodrigo 12, 13 Detlef Koschny 14 Hans Rickman 15, 16 Horst Uwe Keller 17 Michael F. A'Hearn 18, 19 Jessica Agarwal 11 Anne-Thérèse Auger 6 M. Antonella Barucci 20 Jean-Loup Bertaux 21 Ivano, Bertini 1 Sebastien Besse 22 Dennis Bodewits 19 Claire Capanna 6 Vania da Deppo 3 Björn Davidsson 16 Stefano Debei 23 Mariolino de Cecco 24 Francesca Ferri 1 Sonia Fornasier 20 Marco Fulle 25 Robert Gaskell 26 Olivier Groussin 6 Pedro J. Gutiérrez 27 Carsten Güttler 11 Stubbe F. Hviid 10, 11 Wing-Huen Ip 28 Jörg Knollenberg 10 Gabor Kovacs 11 Rainer Kramm 11 Ekkehard Kührt 10 Michael Küppers 29 Fiorangela La Forgia 4 Luisa M. Lara 27 Monica Lazzarin 4 Zhong-Yi Lin 28 Josè J. Lopez Moreno 27 Sara Magrin 4 Harald Michalik 30 Stefano Mottola 10 Nilda Oklay 11 Antoine Pommerol 9 Nicolas Thomas 9 Cecilia Tubiana 11 Jean-Baptiste Vincent 11 
LATMOS - Laboratoire Atmosphères, Milieux, Observations Spatiales
Abstract : The factors shaping cometary nuclei are still largely unknown, but could be the result of concurrent effects of evolutionary and primordial processes. 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 lobes. 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.
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Submitted on : Wednesday, June 8, 2016 - 3:48:35 PM
Last modification on : Thursday, September 29, 2022 - 8:44:06 PM



Matteo Massironi, Emanuele Simioni, Francesco Marzari, Gabriele Cremonese, Lorenza Giacomini, et al.. Two independent and primitive envelopes of the bilobate nucleus of comet 67P. Nature, Nature Publishing Group, 2015, 526, pp.402 - 405. ⟨10.1038/nature15511⟩. ⟨insu-01328952⟩



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