Shakhbazian compact groups: Poor clusters of galaxies

¹ Instituto Nacional de Astrofísica Optica y Electrónica, AP 51 y 216, 72000 Puebla, Pue., México e-mail: hrant@inaoep.mx
² Sternwarte Königsleiten, München, Germany e-mail: htiersch@uni.de

Corresponding author: H. M. Tovmassian, hrant@inaoep.mx

Received: 3 May 2001
Accepted: 26 July 2001

Abstract

The environment of 105 elongated () ShCGs is investigated for galaxies probably associated with them. Counts of galaxies are made in two reciprocally orthogonal stripes of width and length passing through the center of each elongated group. The orientation of the first stripe is determined by the orientation of elongation of the distribution of the principal members of groups. It is found that there is an excess of galaxies in the narrow stripes oriented along the elongation of the group. Such peculiar distribution of the loose group members allows us to conclude that they are gravitationally bound with the compact group, and rotate around the common gravitational center. It is shown that the new-found distant members compose, together with the principal members of the compact group, a gravitationally bound, and, most probably, virialized system. All members of the system rotate around the common gravitational center. It is concluded that ShCGs are the cores of poor clusters of galaxies. They must be not young, and are relatively stable configurations. The number of such groups could be very high in the Universe.