翻訳と辞書
Words near each other
・ Virgo Vibes
・ Virgo Williams
・ Virgocentric flow
・ Virgohamna
・ VIRGOHI21
・ Virgolândia
・ Virgos Merlot
・ Virgularia
・ Virgulariidae
・ Virgílio Lopes
・ Virgílio Mendes
・ Virgínia
・ Viria Sugar Mill
・ Virial coefficient
・ Virial expansion
Virial mass
・ Virial stress
・ Virial theorem
・ Viriat
・ Viriato da Cruz
・ Viriato de Barros
・ Viriato Díaz Pérez
・ Viriato Fiallo
・ Viriatos
・ Viriatus
・ Viribus Unitis
・ Viricelles
・ Viriclanis
・ Viriconium
・ Viriconium (1988 collection)


Dictionary Lists
翻訳と辞書 辞書検索 [ 開発暫定版 ]
スポンサード リンク

Virial mass : ウィキペディア英語版
Virial mass

In astronomy, the virial mass has different meanings depending on the context.
In the context of dark matter halos of galaxies or galaxy clusters, virial mass refers to the mass within the virial radius r_, a radius within which a spherical "top hat" density perturbation destined to become a galaxy is collapsing. This radius is defined as where \rho( where \rho( is the halo's average density within that radius, and \rho_c is the critical density of the universe. (Sometimes in the definition, \rho_c is replaced with the mean density of matter, \rho_M = \Omega_M \rho_c, where, at the present day, \Omega_M \simeq 0.27 according to data fitted to the Lambda-CDM model.) The virial mass is the mass within this radius and hence is a reasonable measure of the total mass inside a dark matter halo, because beyond that radius the halo blends into the background matter in the universe. This definition is not universal, however, as the exact value of \Delta_c depends on the cosmology – in practice, to improve communication, it is sometimes simply assumed that \Delta_c = 200 and hence this is sometimes denoted as M_ = M(, or the total mass contained within the virial radius.
In other contexts, it may refer to the mass inferred from the rotation curve or velocity dispersion of a bound collection of stars, assuming the virial theorem applies.
==References==



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「Virial mass」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.