CO in blue compact and star burst galaxies

Abstract

$^{12}CO(J=1 \to 0)$ observations of 34 blue compact and star burst galaxies are presented. Although these galaxies are experiencing vigorous star formation at the current epoch, CO has been detected in only five of them. The five detections reported in this paper are all in galaxies with relatively red colours, (B-V)_0 > 0.4. The new observations, when combined with previously published data on CO in BCGs, indicate that CO luminosity decreases with absolute luminosity of BCGs. Since the absolute luminosity of a galaxy is correlated with its metallicity, these results confirm that low metallicity BCGs have low abundances of CO gas. We also show that the star formation rate determined from the $H_β$ luminosity is lower than that determined from the far infrared luminosity.