Work

Time-varying Dynamical Star Formation Rate

Year: 2015

Type: article

Abstract: We present numerical evidence of dynamic star formation in which the accreted stellar mass grows superlinearly with time, roughly as t 2 . We perform simulations of star formation in self-gravitating hydrodynamic and magnetohydrodynamic turbulence that is continuously driven. By turning the self-gravity of the gas in the simulations on or off, we demonstrate that self-gravity is the dominant physical effect setting the mass accretion rate at early times before feedback effects take over, contrary to theories of turbulence-regulated star formation. We find that gravitational collapse steepens the density profile around stars, generating the power-law tail on what is otherwise a lognormal density probability distribution function. Furthermore, we find turbulent velocity profiles to flatten inside collapsing regions, altering the size–line width relation. This local flattening reflects enhancements of turbulent velocity on small scales, as verified by changes to the velocity power spectra. Our results indicate that gas self-gravity dynamically alters both density and velocity structures in clouds, giving rise to a time-varying star formation rate. We find that a substantial fraction of the gas that forms stars arrives via low-density flows, as opposed to accreting through high-density filaments.

Source: The Astrophysical Journal

DOI: 10.1088/0004-637x/800/1/49

Authors: Eve J. Lee, Philip Chang, Norman Murray

Institutions: University of Toronto, Canadian Institute for Theoretical Astrophysics, University of California, Berkeley, University of Wisconsin–Milwaukee

Language: English

Topic: Astrophysics and Star Formation Studies

Subfield: Astronomy and Astrophysics

Field: Physics and Astronomy

Domain: Physical Sciences

Open Access status: bronze