HI stripping and color evolution of the VIVA galaxies

We present the result from our color bimodality study of spirals in a single cluster environment using the VIVA (VLA Imaging Survey of Virgo in Atomic gas) sample. The goal is to investigate whether HI gas stripping in the cluster plays a role in moving galaxies from the blue cloud to the red sequence. We explore the dependence of the color-magnitude relation on HI properties such as morphology and deficiency, and how the relation compares to the SDSS sample. We find that severely gas stripped galaxies with small HI disks are redder compared to gas rich galaxies with extended HI disks with a few exceptions. Among the most gas deficient systems, the ones showing signatures of recent stripping appear to be bluer than the galaxies that are likely to have been stripped a while ago. In particular, five out of seven galaxies with one-sided extended HI tails, which are thought to be falling into the cluster for the first time, are found somewhere between the blue cloud and the red sequence in the region known as "green valley". These imply that galaxies become redder due to quenching of star formation as they lose gas in high density regions (e.g. clusters). While not the only effect, it appears that HI stripping in the cluster environment is one of the contributors to color evolution.