颖神星
维库，知识与思想的自由文库
5个分类: 正在翻譯的條目 | Main Belt asteroids | Asteroids named from Greek mythology | S-type asteroids | 来自中文维基百科
穎神星（亦稱9號小行星）是小行星帶較大的小行星之一，由矽酸鹽、鎳和鐵組成，並且有可能是古代一顆巨大的小行星撞擊后的核心殘留物。
[编辑] 發現和命名穎神星是由Andrew Graham於1848年4月25日發現，是他發現的唯一一顆小行星。它也是唯一一顆在愛爾蘭觀測發現的小行星。名稱的由來是神話中的泰坦女神和海洋女神墨提斯，是太西絲和海洋之神的女兒。西蒂斯這個名稱也曾經被提議，但後來被否決了（名稱後來被用在17海女星）。 [编辑] 特性基於資料不明確，穎神星自轉方向至今仍不明。 Lightcurve analysis indicates that Metis' pole points towards either ecliptic coordinates (β, λ) = (23°, 181°) or (9°, 359°) with a 10° uncertainty.[1] The equivalent equatorial coordinates are (α, δ) = (12.7 h, 21°) or (23.7 h, 8°). This gives an axial tilt of 72° or 76°, respectively.[來源請求]
The surface composition has been estimated as 30-40% metal-bearing olivine and 60-70% Ni-Fe metal.[10] Light curve data on Metis led to an assumption that it could have a satellite. However, subsequent observations failed to confirm this.[11][12] Later searches with the Hubble Space Telescope in 1993 found no satellites.[8] [编辑] Family relationshipsMetis was once considered to be a member of an asteroid family known as the Metis family,[13] but more recent searches for prominent families did not recognize any such group, nor is a clump evident in the vicinity of Metis by visual inspection of proper orbital element diagrams. However, a spectroscopic analysis found strong spectral similarities between Metis and 113 Amalthea, and it is suggested that these asteroids may be remnants of a very old (at least ~1 Ga) dynamical family whose smaller members have been pulverised by collisions or perturbed away from the vicinity. The putative parent body is estimated to have been 300 to 600 km in diameter (Vesta-sized) and differentiated. Metis would be the relatively intact core remnant, and Amalthea a fragment of the mantle.[10] Coincidentally, both Metis and Amalthea have namesakes among Jupiter's inner moons. [编辑] OccultationsMetis has been observed to occult stars no less than 5 times.[14] [编辑] 參見
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