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| 題名: | Dark side of comet 67P/Churyumov-Gerasimenko in Aug.-Oct. 2014: MIRO/Rosetta continuum observations of polar night in the southern regions |
| 作者: | 葉永烜;Choukroun, M.;Keihm, S.;Schloerb, F. P.;Gulkis, S.;Lellouch, E.;Leyrat, C.;von Allmen, P.;Biver, N.;Bockelée-Morvan, D.;Crovisier, J.;Encrenaz, P.;Hartogh, P.;Hofstadter, M.;Ip, W.-H.;Jarchow, C.;Janssen, M.;Lee, S.;Rezac, L.;Beaudin, G.;Gaskell, B.;Jorda, L.;Keller, H. U.;Sierks, H. |
| 貢獻者: | 理學院天文研究所 |
| 關鍵詞: | Astrophysics;Channels;Comets;Continuums;Mathematical models;Night;Nuclei;Polar regions;Sciences of the Universe;Specific heat |
| 日期: | 2015-11-01 |
| 上傳時間: | 2026-04-21 14:39:49 (UTC+8) |
| 出版者: | EDP Sciences |
| 摘要: | 摘要： The high obliquity (~50[degrees]) of comet 67P/Churyumov-Gerasimenko (67P) is responsible for a long-lasting winter polar night in the southern regions of the nucleus. We report observations made with the submillimeter and millimeter continuum channels of the Microwave Instrument onboard the Rosetta Orbiter (MIRO) of the thermal emission from these regions during the period August-October 2014. Before these observations, the southern polar regions had been in darkness for approximately five years. Subsurface temperatures in the range 25-50 K are measured. Thermal model calculations of the nucleus near-surface temperatures carried out over the orbit of 67P, coupled with radiative transfer calculations of the MIRO channels brightness temperatures, suggest that these regions have a thermal inertia within the range 10-60 J m super(-2) K super(-1) s super(-0.5). Such low thermal inertia values are consistent with a highly porous, loose, regolith-like surface. These values are similar to those derived elsewhere on the nucleus. A large difference in the brightness temperatures measured by the two MIRO continuum channels is tentatively attributed to dielectric properties that differ significantly from the sunlit side, within the first few tens of centimeters. This is suggestive of the presence of ice(s) within the MIRO depths of investigation in the southern polar regions. These regions started to receive sunlight in May of 2015, and refinements of the shape model in these regions, as well as continuing MIRO observations of 67P, will allow refining these results and reveal the thermal properties and potential ice content of the southern regions in more detail.
出版者： EDP Sciences
出版日期： 2015-11
出處： Astronomy and astrophysics (Berlin), 2015-11, Vol.583, p.A28
資源來源： EDP Sciences
版權： licence_http://creativecommons.org/publicdomain/zero
識別號： ISSN: 0004-6361
識別號： EISSN: 1432-0746
識別號： DOI: 10.1051/0004-6361/201526181 |
| 顯示於類別: | [天文研究所] 期刊論文
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