Neutral hydrogen around early-type galaxies

When early-type (E,S0) galaxies have neutral hydrogen very extended region. This suggests several possible origins for the gas, either intrinsic to the galaxy or from an external source. We present 21 cm H I maps around early-type galaxies to study the distribution of gas in the galaxies' vicinity and address these possibilities. We examine two sets of objects: (1) early-type galaxies with conflicting H I measurements that might indicate unusual gas distributions, and (2) galaxy groups that are dominated by early-type galaxies. We have identified several galaxies with extended H I disks, and a number of H I companions that may be interacting with the early-type galaxies and may be confusing H I observations. Many of the companions can be optically associated with uncataloged dwarf galaxies, but a few are quite peculiar or have no clear optical association. We discuss the implications of these results for the origin of H I in early-type galaxies. (C) 1996 American Astronomical Society.