STAR-FORMATION IN BCD GALAXIES OF THE VIRGO CLUSTER

We studied a sample of blue compact dwarf galaxies in the Virgo cluste r to understand the dependence of star formation processes in galaxies devoid of large patterns of star formation. The galaxies were selecte d to have HI data and were observed in optical bands and in the UV. Th e star formation rates were calculated and were compared for different galaxies. We found no difference in the rates of star formation among galaxies with high HI content and low HT content, as well as no depen dence on Virgocentric distance. Evolutionary population synthesis fits indicate that a preferred explanation of the BCD phenomenon is of sho rt, a few Myrs long bursts of star formation, followed by a few Gyrs o f quiescence. This pattern probably repeats a number of times in the l ifetime of a galaxy. The efficiency of star formation is not significa ntly different from that in large spiral galaxies.