Title: VIVA, The New VLA HI Imaging survey of Virgo galaxies in Atomic gas
     - The art telling the galaxy evolution in the cluster environment

Aeree Chung (NRAO/UMass)

Much observational evidence has been accumulated that galaxies get affected
by their surroundings. It has been suggested that ram-pressure stripping,
thermal evaporation, starvation, and tidal effects can all affect galaxies.
However, the impact of these processes on individual galaxies in regions of
different density is still not well understood. As a nearby and dynamically
young galaxy cluster, Virgo is an ideal place to study details of these
mechanisms at work. In this talk, I present the result of a recent VLA HI
imaging study of 53 galaxies which were carefully selected throughout the
Virgo cluster from near the dense core to the outskirt. Our high resolution
and sensitivity HI data have revealed different stages of both hydrodynamic
and tidal effects. I will show examples of how we trace what each galaxy
has gone through or is currently experiencing in the cluster using the HI
morphology and kinematics. We also have explored the efficiency of various
processes as a function of projected distance from the cluster center. Gas-
gas and galaxy-galaxy interactions appear to be dominant in high and low
density regions, respectively. In intermediate density regions, we see the
hints of the mixture of both, which are likely to cause "pre-processing" in 
infalling galaxies.