SIMBAD references

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, NGC 4286 and NGC 4310. CO(1-0) and (2-1) lines have been detected and mapped in three galaxies. We present a comparison of the amount of molecular and atomic hydrogen in these galaxies with the expected amounts drawn from samples found in the literature. It is clear that most of the group galaxies have lower than average total gas masses, due to a large deficiency of atomic hydrogen. Despite the large dispersion present 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 clusters, but can be found also in dense galaxy groups. The CO emission of the galaxies, hence presumably their H₂ content, is however not affected by the environment; this conclusion holds for the group galaxies as well as for the spirals previously studied in the Virgo and Coma clusters.