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In astrometry, the moving cluster method and the closely related convergent point method are means, primarily of historical interest, for determining the distance to star clusters. They were used on several nearby clusters in the first half of the 1900s to determine distance. The method is now largely superseded by other, usually more accurate distance measures. ==Introduction== The moving cluster method relies on observing the proper motions and doppler shift of each member of a group of stars known to form a cluster. The idea is that since all the stars are close together, they will tend to move towards a common convergence point on the sky. This is essentially a perspective effect. Using the moving cluster method, the distance to a given star cluster can be determined using the following equation: : where "u" represents the proper motion of the cluster. 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「Moving cluster method」の詳細全文を読む スポンサード リンク
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