Metal Transport to the Gaseous Outskirts of Galaxies
  We present a search for outlying HII regions in the extended gaseous
outskirts of nearby (D < 40 Mpc) galaxies, and subsequent multi-slit
spectroscopy used to obtain the HII region nebular oxygen abundances. The
galaxies in our sample have extended HI disks and/or interaction-related HI
features that extend well beyond their primary stellar components. We report
oxygen abundance gradients out to 2.5 times the optical radius for these
galaxies which span a range of morphologies and masses. We analyze the
underlying stellar and neutral HI gas distributions in the vicinity of the HII
regions to understand the physical processes that give rise to the observed
metal distributions in galaxies. These measurements, for the first time,
convincingly show flat abundance distributions out to large radii in a wide
variety of systems, and have broad implications for galaxy chemodynamical
evolution.
