Stars and Gas in Clusters: Feedback, Efficiency and Emergence

Abstract

Star clusters are born immersed in molecular gas and hidden by huge extinction. Their evolution is determined by how the young stars interact with the gas and especially on the efficiency with which the gas is turned into stars. The high pressure of starburst regions encourages cloud collapse and cluster formation; the most massive proto-clusters forming in the Local Universe are over-pressured by accreting molecular filaments. Stellar winds can combine to form cluster super-winds that clear away the gas (negative feedback) or that stall inside the cluster to create a second generation of stars from enriched material (positive feedback). We review recent observations and models of young clusters in the embedded and emerging stages.