| Abstract | Results are presented of 21-cm VLA observations of the late-type spiral galaxies UGC 12423 and NGC 7591, both located in the Pegasus I cluster of galaxies. The optical image of UGC 12423 reveals the galaxy to be highly flattened, possessing a thin optical disk that is noticeably warped. Its 21-cm observations show a similar morphology for the H I and suggests a rising rotation curve as well. These features may explain the galaxy's discrepant location in the infrared Tully-Fisher diagram. The observations of UGC 12423 reveal that the total linear extent of the H I is at least 60 kpc (H(0) = 100 km/sec per Mpc), which exceeds the optical image of the galaxy by about 50%. Comparable conclusions apply to NGC 7591, but with less certainty. The existence of extended H I in cluster galaxies may imply that a significant interaction (i.e., stripping) with the environment has not yet occurred. |
