Hickson compact groups: The cores of elongated loose groups

Evidence is presented which indicates that almost all HCGs are dynamically associated with generally elongated loose groups of galaxies, and are compact cores of the latter. Most of those loose groups, the direction of elongation of which lies at angles close to 45 degrees with the line of sight, were revealed by previous investigations. Hence, HCGs have, probably, longer life-times than it has been deduced from N-body simulations, and thus are more stable configurations. The remote members of HCGs (the members of loose groups) are gravitationally bound with them.