GALAXIES WITH A LOW GAS CONTENT IN THE COMA-I CLOUD OF GALAXIES

We have observed the CO emission of six galaxies belonging to a small dense group: NGC 4245, NGC 4251, NGC 4274, the elliptical NGC 4278, NG C 4286 and NGC 4310. C0(1-0) and (2-1) lines have been detected and ma pped in three galaxies. We present a comparison of the amount of molec ular and atomic hydrogen in these galaxies with the expected amounts d rawn from samples found in the literature. It is clear that most of th e group galaxies have lower than average total gas masses, due to a la rge deficiency of atomic hydrogen. Despite the large dispersion presen t in the CO emission of galaxies, their content of molecular gas lies in the expected range given their rather early types. This study shows that galaxies strongly deficient in HI do not exclusively belong to c lusters, but can be found also in dense galaxy groups. The CO emission of the galaxies, hence presumably their H-2 content, is however not a ffected by the environment; this conclusion holds for the group galaxi es as well as for the spirals previously studied in the Virgo and Coma clusters.