Star formation at compressed interfaces in turbulent self-gravitating clouds

Abstract

Supersonic turbulence in both self-gravitating and diffuse clouds can produce self-similar, hierarchical density structures and broad line-wings on a wide range of scales, making these two cloud types look similar and giving the clumps in each the same scaling laws. We show here that the dense compressed regions that form between converging turbulent flows should collapse to form dense cores and ultimately stars in self-gravitating clouds, whereas they only disperse and reform intermittently in diffuse clouds. Star formation in turbulence-compressed regions should be as hierarchical as the turbulence, leading to clusters and multiple star systems instead of single stars; some binary stars may form by gravitational capture of stars in nearby turbulent clumps. Reasonable mass functions for clumps and stars are estimated from the theory. The slope of the initial stellar mass function is steeper than that for the clumps because of the increasing lifetime for clumps with larger mass.