STAR-FORMATION AND MERGING IN COMPACT-GROUPS OF GALAXIES

New UBV aperture photometry for 177 galaxies in Hickson compact groups is presented. The analysis of the color-color diagram indicates that, contrary to what one naively would expect, only a slight enhancement in their star formation rates is present. The results are confirmed by the analysis of the IRAS data, taking in particular into account the 25 mum detections. Star formation in compact groups is not found to be higher than in isolated pairs of galaxies. Earlier results on the absence of clear candidates for merger products of late type galaxies are confirmed and strengthened. It is pointed out that the relation between velocity dispersion and morphological mixing found for Hickson groups could be one of the clues to understand the evolution of galaxies in them.