Systematic properties of compact groups of galaxies

One hundred compact groups of galaxies have been identified by a systematic search of the Palomar Observatory Sky Survey red prints. Each group contains four or more galaxies within a 3 mag range, has an estimated mean surface brightness brighter than 26.0 mag arcsec-1, and satisfies an isolation criterion. An analysis of estimated galaxy magnitudes, morphology, and group angular size indicates: (1) There is no correlation between group density and magnitude difference between the first and second-ranked galaxies, and no preferred morphological type for the first-ranked galaxies, many of which are spiral. (2) The groups contain fewer spirals than a comparable sample of field galaxies. The spiral fraction decreases from 60% in the least compact groups which do not. (3) There appears to be a deficiency of faint galaxies in comparison with rich cluster and field galaxies. This apparent deficiency is more severe in groups with elliptical first-ranked galaxies. Possible implications of these results for dynamical evolution are considered