OSIRIS observations of meter-sized exposures of H2O ice at the surface of 67P/Churyumov-Gerasimenko and interpretation using laboratory experiments

Please use this identifier to cite or link to this item: https://ir.lib.ncu.edu.tw/handle/987654321/101700

Title:	OSIRIS observations of meter-sized exposures of H2O ice at the surface of 67P/Churyumov-Gerasimenko and interpretation using laboratory experiments
Authors:	葉永烜;Pommerol, A.;Thomas, N.;El-Maarry, M. R.;Pajola, M.;Groussin, O.;Auger, A.-T.;Oklay, N.;Fornasier, S.;Feller, C.;Davidsson, B.;Gracia-Berná, A.;Jost, B.;Marschall, R.;Poch, O.;Barucci, M. A.;Bertaux, J.-L.;La Forgia, F.;Keller, H. U.;Kührt, E.;Lowry, S. C.;Mottola, S.;Naletto, G.;Sierks, H.;Barbieri, C.;Lamy, P. L.;Rodrigo, R.;Koschny, D.;Rickman, H.;Agarwal, J.;A’Hearn, M. F.;Bertini, I.;Boudreault, S.;Cremonese, G.;Da Deppo, V.;De Cecco, M.;Debei, S.;Güttler, C.;Fulle, M.;Gutierrez, P. J.;Hviid, S. F.;Ip, W.-H.;Jorda, L.;Knollenberg, J.;Kovacs, G.;Kramm, J.-R.;Küppers, E.;Lara, L.;Lazzarin, M.;Lopez Moreno, J. L.;Marzari, F.;Michalik, H.;Preusker, F.;Scholten, F.;Tubiana, C.;Vincent, J.-B.
Contributors:	理學院天文研究所
Keywords:	comets: general;methods: laboratory: solid state;techniques: image processing
Date:	2015-11-01
Issue Date:	2026-04-21 14:41:10 (UTC+8)
Publisher:	EDP Sciences
Abstract:	摘要： Since OSIRIS started acquiring high-resolution observations of the surface of the nucleus of comet 67P/Churyumov-Gerasimenko, over one hundred meter-sized bright spots have been identified in numerous types of geomorphologic regions, but mostly located in areas receiving low insolation. The bright spots are either clustered, in debris fields close to decameter-high cliffs, or isolated without structural relation to the surrounding terrain. They can be up to ten times brighter than the average surface of the comet at visible wavelengths and display a significantly bluer spectrum. They do not exhibit significant changes over a period of a few weeks. All these observations are consistent with exposure of water ice at the surface of boulders produced by dislocation of the weakly consolidated layers that cover large areas of the nucleus. Laboratory experiments show that under simulated comet surface conditions, analog samples acquire a vertical stratification with an uppermost porous mantle of refractory dust overlaying a layer of hard ice formed by recondensation or sintering under the insulating dust mantle. The evolution of the visible spectrophotometric properties of samples during sublimation is consistent with the contrasts of brightness and color seen at the surface of the nucleus. Clustered bright spots are formed by the collapse of overhangs that is triggered by mass wasting of deeper layers. Isolated spots might be the result of the emission of boulders at low velocity that are redepositioned in other regions. 出版者： EDP Sciences 出版日期： 2015-11-01 出處： Astronomy & Astrophysics, 2015-11, Vol.583, p.A25- 資源來源： EDP Sciences 識別號： ISSN: 0004-6361 識別號： ISSN: 1432-0746 識別號： EISSN: 1432-0746 識別號： DOI: 10.1051/0004-6361/201525977
Appears in Collections:	[Graduate Institute of Astronomy] journal & Dissertation

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