摘要
本文利用由Binggeli、Sandage和Tammann提供的Virgo团天区星系视向速度所确定的6°核区域的352个成员星系,得出团的Virial质量为μv=2.7×10^(14)μ。总光度L_B=2.0×10^(12)L,质光比μv/L_B=136,以及光度质量μ_L=4.1×10^(13)μ,Virgo团有着和Coma团类似的速度弥散度轮廓,近团中心部分的星系速度弥散度有减小的趋势。团星系呈现明显的形态分层,早型星系较之晚型星系明显向团中心聚集,速度弥散度较小(615:827公里·秒^(-1))。分析表明,Virgo团所经历的动力学演化过程很短,质量分层效应很不显著,是一个年轻的不规则星系团。
From line-of-sight velocities of galaxies in the Virgo cluster region given by Binggeli.Sandage and Tammann according to the maximum likelihood principle,352 member galaxies in central 6° core of the cluster are determined. Based on these member galaxies it is obtained that for the cluster the virial mass μv= 2.7 × 1014μ, total luminosity LB = 2.0 × 10l2Le, mass-luminosity ratio μv/LB= 136, and luminosity mass μL = 4.1 × 1013μ. The velocity dispersion profile of the Virgo cluster is quite similar to that of the Coma, and a tendency is found for the observed velocity dispersion decreasing towards the cluster center. There is a strong morphological segregation in both space and velocity for the cluster members, early-type galaxies being more concentrated towards the cluster center and showing a smaller velocity dispersion than late types (σ = 615 versus 827 km f77 s-1). It is indicated from discussions on the virial mass and the mass segregation that the period of dynamic evolution when the Virgo cluster has been undergone is relatively quite short, there is shown almost no effect of mass segregation, and it should be a young irregular cluster of galaxies.
