Anomalous HI in NGC 2997
  We present deep HI observations of the moderately inclined spiral galaxy, NGC
2997. The goal of these observations was to search for HI clouds in the
vicinity of NGC 2997 analogous to the high velocity clouds of the Milky Way and
gain insight into their origins. We find evidence for the presence of a
galactic fountain as well as the accretion of intragalactic material, however
we do not identify any large clouds of HI far from the disk of the galaxy. NGC
2997 has a thick, lagging HI disk that is modeled with a vertical velocity
gradient of 18-31 km/s/kpc. Anomalous velocity HI clouds with masses of order
10^7 Msun, which cannot be explained by galactic fountain models allow us to
estimate a lower limit to the accretion of extragalactic gas of 1.2 Msun/yr.
The number and mass of these clouds have implications for cosmological
simulations of large scale structure and the presence of dark matter halos. We
have used values from the the literature to estimate a star formation rate of 5
+/- 1 Msun/yr and to derive a new distance to NGC 2997 of 12.2 +/- 0.9 Mpc
using published Tully-Fisher relations.
