Molecular Clouds: Formation and Disruption

Star cluster disruption by giant molecular clouds

We investigate encounters between giant molecular clouds (GMCs) and star clusters. We propose a single expression for the energy gain of a cluster due to an encounter with a GMC, valid for all encounter distances and GMC properties. This relation is verified with N -body simulations of cluster-GMC encounters, where the GMC is represented by a moving analytical potential. Excellent agreement is ...

The Formation of Molecular Clouds

In a recent paper, Elmegreen (2000) has made a cogent case, from an observational point of view, that the lifetimes of molecular clouds are comparable to their dynamical timescales. If so, this has important implications for the mechanisms by which molecular clouds form. In particular we consider the hypothesis that molecular clouds may form not by in situ cooling of atomic gas, but rather by t...

The Disruption of Giant Molecular Clouds by Radiation Pressure & the Efficiency of Star Formation in Galaxies

Star formation is slow, in the sense that the gas consumption time is much longer than the dynamical time. It is also inefficient; essentially all star formation in local galaxies takes place in giant molecular clouds (GMCs), but the fraction of a GMC converted to stars is very small, ∼ 5%. While there is some disagreement over the lifespan of GMCs, there is a consensus that it is no more than ...

The Formation of Distributed and Clustered Stars in Molecular Clouds The Formation of Distributed and Clustered Stars in Molecular Clouds

Cluster Formation in Contracting Molecular Clouds

We explore, through a simplified, semianalytic model, the formation of dense clusters containing massive stars. The parent cloud spawning the cluster is represented as an isothermal sphere. This sphere is in nearYforce balance between self-gravity and turbulent pressure. Self-gravity, mediated by turbulent dissipation, drives slow contraction of the cloud, eventually leading to a sharp central ...