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

Please use this identifier to cite or link to this item: https://ir.lib.ncu.edu.tw/handle/987654321/101623

Title:	Two independent and primitive envelopes of the bilobate nucleus of comet 67P
Authors:	林忠義;Massironi, Matteo;Simioni, Emanuele;Marzari, Francesco;Cremonese, Gabriele;Giacomini, Lorenza;Pajola, Maurizio;Jorda, Laurent;Naletto, Giampiero;Lowry, Stephen;El-Maarry, Mohamed Ramy;Preusker, Frank;Scholten, Frank;Sierks, Holger;Barbieri, Cesare;Lamy, Philippe;Rodrigo, Rafael;Koschny, Detlef;Rickman, Hans;Keller, Horst Uwe;A’Hearn, Michael F.;Agarwal, Jessica;Auger, Anne-Thérèse;Barucci, M. Antonella;Bertaux, Jean-Loup;Bertini, Ivano;Besse, Sebastien;Bodewits, Dennis;Capanna, Claire;Da Deppo, Vania;Davidsson, Björn;Debei, Stefano;De Cecco, Mariolino;Ferri, Francesca;Fornasier, Sonia;Fulle, Marco;Gaskell, Robert;Groussin, Olivier;Gutiérrez, Pedro J.;Güttler, Carsten;Hviid, Stubbe F.;Ip, Wing-Huen;Knollenberg, Jörg;Kovacs, Gabor;Kramm, Rainer;Kührt, Ekkehard;Küppers, Michael;La Forgia, Fiorangela;Lara, Luisa M.;Lazzarin, Monica;Lin, Zhong-Yi;Lopez Moreno, Josè J.;Magrin, Sara;Michalik, Harald;Mottola, Stefano;Oklay, Nilda;Pommerol, Antoine;Thomas, Nicolas;Tubiana, Cecilia;Vincent, Jean-Baptiste
Contributors:	理學院天文研究所
Keywords:	639/33/445/215;639/33/445/848;704/2151/536;704/445/848;Accretion;Astrophysics;Comets;Earth and Planetary Astrophysics;Excavation;Geology;Humanities and Social Sciences;letter;multidisciplinary;Observations;Physics;Science;Sciences of the Universe;Space exploration;Stratigraphy
Date:	2015-10-15
Issue Date:	2026-04-21 14:39:27 (UTC+8)
Publisher:	Nature Publishing Group;London: Nature Publishing Group UK
Abstract:	摘要： The ‘onion-like’ stratification of the two lobes of the comet 67P/Churyumov–Gerasimenko reveals that its unusual shape is the result of a gentle collision merging two kilometre-sized objects in the early stages of the Solar System. A comet of two halves The Rosetta space probe has shown comet 67P/Churyumov–Gerasimenko to have an unusual bilobed shape, raising the question of whether it is a single monolithic body that eroded unevenly through localized outgassing, or the expression of two distinct accreted objects. Matteo Massironi et al . 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. These factors suggest that comet 67P is an accreted body of two distinct objects with 'onion-like' stratification, formed before they merged. The factors shaping cometary nuclei are still largely unknown, but could be the result of concurrent effects of evolutionary 1 , 2 and primordial processes 3 , 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 lobes 5 . 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. 其他題名： Nature 出版者： London: Nature Publishing Group UK 出版日期： 2015-10-15 出處： Nature (London), 2015-10, Vol.526 (7573), p.402-405 資源來源： Nature Journals 版權： Springer Nature Limited 2015 版權： COPYRIGHT 2015 Nature Publishing Group 版權： Copyright Nature Publishing Group Oct 15, 2015 版權： CC0 1.0 - Universal 識別號： ISSN: 0028-0836 識別號： ISSN: 1476-4687 識別號： EISSN: 1476-4687 識別號： DOI: 10.1038/nature15511 識別號： PMID: 26416730 識別號： CODEN: NATUAS
Appears in Collections:	[Graduate Institute of Astronomy] journal & Dissertation

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