Open clusters in a dispersing molecular cloud

Star clusters are formed in molecular clouds which are believed to be the birth places of most stars. From recent observational data, Lada & Lada(2003) estimated that only 4 to 7% of the proto-clusters have survived. Many factors could cause this high infant mortality. Galactic tidal forces, close encounters with molecular clouds and shock heating are among the possible causes but they have a longer timescale than typical lifetime of molecular clouds. Another possible reason is mass loss in very beginning of cluster evolution in the form of UV radiation, stellar winds or supernova explosions. Mass loss is the main factor we study in this work by using N-body simulations. We find that most proto-clusters survive for more than 40 Myr even when the mass loss rate is high.