COMPACT-GROUPS OF GALAXIES

Compact groups of galaxies have posed a number of challenging question s. Intensive observational and theoretical studies are now providing a nswers to many of these and, at the same time, are revealing unexpecte d new clues about the nature and role of these systems. Most compact g roups contain a high fraction of galaxies having morphological or kine matical peculiarities, nuclear radio and infrared emission, and starbu rst or active galactic nuclei (AGN) activity. They contain large quant ities of diffuse gas and are dynamically dominated by dark matter. The y most likely form as subsystems within looser associations and evolve by gravitational processes. Strong galaxy interactions result and mer ging is expected to lead to the ultimate demise of the group. Compact groups are surprisingly numerous and may play a significant role in ga laxy evolution.