Groups of galaxies in the local supercluster: some hypotheses on the evolutionary stage

Journal ArticleWe present a method capable of determining the evolutionary stage of bound, isolated systems of galaxies. In particular, we apply it to a sample of groups, belonging to the Local Supercluster, taken from the Geller and Huchra's (1983) catalogue. We find that most of them are still in the phase of collapse and not yet virialized. Their evolutionary stages are distributed around that of the Virgo cluster, which lies in a central position in the region considered. Moreover, the knowledge of the evolutionary stage of a system permits the determination of its mass even when it is not in virial equilibrium. The median M/L ratio of the groups in our sample proves to be in the range (550-700) hMo/L0(B) (H0 =/h1OO kms -1 Mpc-1)