The Evolution of Molecular Clouds: Turbulence-regulated Global Radial Collapse

Abstract

The star formation efficiency (SFE) measures the proportion of molecular gas converted into stars, while the star formation rate (SFR) indicates the rate at which gas is transformed into stars. Here we propose such a model in the framework of a turbulence-regulated global radial collapse in molecular clouds being in quasi-virial equilibrium, where the collapse velocity depends on the density profile and the initial mass-to-radius ratio of molecular clouds, with the collapse velocity accelerating during the collapse process. This simplified analytical model allows us to estimate a lifetime of giant molecular clouds of approximately 0.44−7.36 × 10 ^7 yr, and a star formation timescale of approximately 0.5–5.88 × 10 ^6 yr. Additionally, we can predict an SFE of approximately 1.59%, and an SFR of roughly 1.85 M _⊙ yr ^−1 for the Milky Way in agreement with observations.

Keywords

• Molecular clouds
• Star formation
• Interstellar medium