Star Formation in Las Campanas Compact Groups

Abstract

Compact groups (CGs) of galaxies offer an exceptional laboratory for the study of dense galactic environments, where interactions, tidally induced activity, and mergers are expected to be at their highest rate of occurrence. Here we present first results from a new catalog of compact groups, one based on the Las Campanas Redshift Survey (LCRS). Using the equivalent width of [O II] λ3727, we have studied the star formation activity in LCRS CGs: we find strong evidence of depressed star formation in CGs relative to that in loose groups or the field. Although much of this effect can be ascribed to a morphological mix (CGs contain a high fraction of early-type galaxies), there is some evidence that the star formation rate in late-type galaxies is particularly deficient—perhaps only one-half to one-third that of field spiral galaxies. We conclude that gas-stripping mechanisms may play a role in CG environments.