翻訳と辞書 Words near each other ・ Gravity Park USA ・ Gravity Payments ・ Gravitational Pull vs. the Desire for an Aquatic Life ・ Gravitational redshift ・ Gravitational shielding ・ Gravitational singularity ・ Gravitational soliton ・ Gravitational Systems ・ Gravitational time dilation ・ Gravitational two-body problem ・ Gravitational wave ・ Gravitational wave background ・ Gravitational Wave International Committee ・ Gravitational-wave astronomy ・ Gravitational-wave observatory ・ Gravitationally aligned orbits ・ Gravitcornutia ・ Gravitcornutia aethesiana ・ Gravitcornutia altoperuviana ・ Gravitcornutia artificiosa ・ Gravitcornutia basiceramea ・ Gravitcornutia bertioga ・ Gravitcornutia camacae ・ Gravitcornutia caracae ・ Gravitcornutia cearae ・ Gravitcornutia cinnamomea ・ Gravitcornutia constricta ・ Gravitcornutia cornuta ・ Gravitcornutia curiosa ・ Gravitcornutia cuspis Dictionary Lists mini英和辞書 mini和英辞書 Webster 1913 Latin-English FOLDOC Wikipedia English ウィキペディア

翻訳と辞書　辞書検索 [ 開発暫定版 ] スポンサード リンク Gravitationally aligned orbits ： ウィキペディア英語版 Gravitationally aligned orbits Stars in a spiral galaxy move in certain orbits under the influence of the gravitational field associated with the totality of stars in that galaxy. The patterns of these orbits have been studied observationally and using simulation methods. From observations of the motions of over 20,000 local stars (within 300 parsecs), and using numerical simulation, Charles Francis and Erik Anderson have shown that, contrary to conventional wisdom, stars tend to move along a spiral arm during the inward part of their orbits, leaving the arm shortly after pericentre crossing the other arm on the outward part of the orbit and rejoining the original arm shortly before apocentre.〔(Proc. R. Soc. A 8 November 2009 vol. 465 no. 2111 3425–3446 )〕 ==Potential in a spiral galaxy== The gravitational potential of a spiral galaxy can be described as a giant, spiral-grooved funnel. The grooves represent the gravitational field of the galaxy's spiral arms. As a star nears apocentre, the slowest part of its orbit, it will tend to fall into a groove. It will then tend to follow the groove, picking up momentum as it goes, on a path closely aligned with an elliptical orbit. Near the innermost part of the orbit, the alignment between the orbital path and the arm comes to an end, and the star gains enough momentum to jump free of its groove. It crosses over the next-highest groove, then falls back to a higher point in its original groove. At the same time, the funnel may rotate slowly, so that orbits form rosettes rather than ovals. Numerical simulation establishes that orbits can precess either prograde or retrograde due to the spiral potential, and that they tend to align with the arms such that the star follows the arm during the inward part of the orbit. The mass of the star contributes to the mass of the arm during this part of the orbit, increasing the potential. Thus, as stars are drawn into an arm, the gravitational field of the arm grows stronger, drawing greater number of stars into the arm, and reinforcing spiral structure. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Gravitationally aligned orbits」の詳細全文を読む スポンサード リンク 翻訳と辞書 : 翻訳のためのインターネットリソース Copyright(C) kotoba.ne.jp 1997-2016. All Rights Reserved.