Coma星系团的研究4.结构与次团结构

Studies on the Coma Cluster 4. Structure and Substructure

本文利用确定的278个视向速度成员星系,讨论了Coma星系团的结构和中心区的次团结构.分析表明,Coma团内星系表现有一定程度的空间形态分层和质量分层,早型星系同晚型星系相比,大质量星系与较小质量星系相比,前者的面分布明显地有向团中心集聚的倾向.按最大似然原理对星系的视向速度的分析表明,Coma团中心区可能存在着次团结构.

The structure of the Coma cluster is discussed on the basis of the 278 member galaxies which have been statistically determined from radial velocity data of galaxies in the region of the cluster. It is shown from detailed analyses that there exist spatial morphological segregation and mass segregation for the member galaxies, and early-type galaxies and more massive galaxies are concentrated towards the cluster center more obviously than late-type galaxies and less massive galaxies respectively. Early-type galaxies and massive galaxies show smaller average projected distances from the cluster center Cproportions both being roughly 1 versus 2).Using the radial velocity data of galaxies in the region of the Coma cluster and a new statistical method based on the maximum likelihood principle, the existence of substructure in the central region of the cluster with distances from the cluster.R≤20' is shown, and,two probable subclusters with members of 37 and 9 can be found from 49 galaxies with m≤15.7mag. in the central region, average radial velocities and corresponding dispersions being (7272,±557km/s) and (5654.±288km/s) respectively.