A Gaseous Group with Unusual Remote Star Formation
  We present VLA 21-cm observations of the spiral galaxy ESO 481-G017 to
determine the nature of remote star formation traced by an HII region found 43
kpc and ~800 km s^-1 from the galaxy center (in projection). ESO 481-G017 is
found to have a 120 kpc HI disk with a mass of 1.2x10^10 Msun and UV GALEX
images reveal spiral arms extending into the gaseous disk. Two dwarf galaxies
with HI masses close to 10^8 Msun are detected at distances of ~200 kpc from
ESO 481-G017 and a HI cloud with a mass of 6x10^7 Msun is found near the
position and velocity of the remote HII region. The HII region is somewhat
offset from the HI cloud spatially and there is no link to ESO 481-G017 or the
dwarf galaxies. We consider several scenarios for the origin of the cloud and
HII region and find the most likely is a dwarf galaxy that is undergoing ram
pressure stripping. The HI mass of the cloud and Halpha luminosity of the HII
region (10^38.1 erg s^-1) are consistent with dwarf galaxy properties, and the
stripping can trigger the star formation as well as push the gas away from the
stars.
