Statistical investigation of the structure of observed multiple systems. I. Compact groups of galaxies

A method is proposed for statistical study of the configurations of multiple systems that permits judgments to be drawn about their static and dynamic properties: oblation or prolation, hierarchy, ring-like structure, rotation, etc. The method is used to investigate a sample of 100 isolated compact groups of galaxies in the list of Hickson. It is shown that the groups have a tendency to prolation. Their mean apparent sphericity is approximately 0.4. Their structures are not found to be hierarchical