How Gas Stripping Transforms the Stellar Populations of Cluster Spiral Galaxies

We present results from a study of the stellar populations of HI-stripped spiral galaxies in the nearby Virgo Cluster. Virgo provides an ideal laboratory to study galaxy-galaxy and galaxy-cluster interactions at a level of detail impossible at higher redshift. A large population of spiral galaxies exists in Virgo with mostly undisturbed stellar disks, but truncated gas disks. By combining optical spectroscopy and UV imaging of these galaxies, we can understand when and where the cluster galaxies are affected by interactions. Analysis of disk stellar populations shows that star formation was cut off in these galaxies within the last 500 Myr, consistent in several cases with being stripped outside the cluster core. This suggests that the "reach" of the intracluster medium is greater than suggested by simple ICM models. Such interactions appear to transform blue star forming galaxies into red, passively-evolving disks.