Gas-Bearing Early-Type Dwarf Galaxies in Virgo: Evidence for Recent
  Accretion
  We investigate the dwarf (M_B> -16) galaxies in the Virgo cluster in the
radio, optical, and ultraviolet regimes. Of the 365 galaxies in this sample, 80
have been detected in HI by the Arecibo Legacy Fast ALFA survey. These
detections include 12 early-type dwarfs which have HI and stellar masses
similar to the cluster dwarf irregulars and BCDs. In this sample of 12, half
have star-formation properties similar to late type dwarfs, while the other
half are quiescent like typical early-type dwarfs. We also discuss three
possible mechanisms for their evolution: that they are infalling field galaxies
that have been or are currently being evolved by the cluster, that they are
stripped objects whose gas is recycled, and that the observed HI has been
recently reaccreted. Evolution by the cluster adequately explains the
star-forming half of the sample, but the quiescent class of early-type dwarfs
is most consistent with having recently reaccreted their gas.
