The Color-Dependent Frequency of XUV Disks In Low-Mass E/S0s
  We identify a high frequency of Type 1 XUV disks, reflecting recent outer
disk star formation, in a sample of 31 E/S0s with stellar masses primarily
below M_* ~ 4 x 10^10 M_sun. Our ~40% identification rate is roughly twice the
20% fraction reported for late-type galaxies. Intriguingly, in the dwarf mass
regime (below M_* ~ 5 x 10^9 M_sun) where gas fractions clearly rise, Type 1
XUV disks occur in ~70% of red-sequence E/S0s but only ~20% of blue-sequence
E/S0s, a population recently linked to active disk rebuilding, especially in
the dwarf regime. Our statistics are preliminary, but could indicate that for
dwarf E/S0s Type 1 XUV disks are primarily related to weak or inefficient
outer-disk star formation rather than to star formation capable of driving
substantial disk growth. Substantial growth may instead be associated with
populations that have low XUV-disk frequency, possibly explaining the similar
~20% frequencies for normal late types and low-mass blue-sequence E/S0s.
