Collapse and Star Formation in Self-gravitating Turbulent Fluids

Mon, November 02, 2015

Observations of star forming regions in the Milky Way have established that stars form in large molecular clouds or GMCs. The spectral lines of these GMCs are usually interpreted as the signature of turbulent motion. The kinetic energy in the turbulence is similar to the gravitational binding energy of the GMC. Work over the last decade suggests that stars form in converging flows in this turbulence. I will describe recent analytic and numerical work that has resulted in a detailed description of the evolution of such converging flows. The star forming regions are never in hydrostatic equilibrium. I will show that the flows set up density structures that do not vary with time; the converging gas flows through fixed run of density onto a central star or star cluster. The collapse drives turbulent motions, resulting in deviations from Larson's Law (the size-linewidth relation), and slowing the inflow velocity below the free-fall rate. However, the infall velocity is proportional to the square root of stellar mass, resulting in a mass accretion rate that grows linearly with time.