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Title: TIME-VARYING DYNAMICAL STAR FORMATION RATE

Abstract

We present numerical evidence of dynamic star formation in which the accreted stellar mass grows superlinearly with time, roughly as t {sup 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.

Authors:
; ;  [1]
  1. Canadian Institute for Theoretical Astrophysics, 60 St. George Street, University of Toronto, Toronto, ON M5S 3H8 (Canada)
Publication Date:
OSTI Identifier:
22364204
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 800; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; COMPUTERIZED SIMULATION; DENSITY; DISTRIBUTION FUNCTIONS; FEEDBACK; FILAMENTS; GRAVITATIONAL COLLAPSE; LINE WIDTHS; MAGNETOHYDRODYNAMICS; MASS; PROBABILITY; STAR ACCRETION; STAR EVOLUTION; STARS; TURBULENCE; VELOCITY

Citation Formats

Lee, Eve J., Chang, Philip, and Murray, Norman, E-mail: evelee@berkeley.edu. TIME-VARYING DYNAMICAL STAR FORMATION RATE. United States: N. p., 2015. Web. doi:10.1088/0004-637X/800/1/49.
Lee, Eve J., Chang, Philip, & Murray, Norman, E-mail: evelee@berkeley.edu. TIME-VARYING DYNAMICAL STAR FORMATION RATE. United States. doi:10.1088/0004-637X/800/1/49.
Lee, Eve J., Chang, Philip, and Murray, Norman, E-mail: evelee@berkeley.edu. Tue . "TIME-VARYING DYNAMICAL STAR FORMATION RATE". United States. doi:10.1088/0004-637X/800/1/49.
@article{osti_22364204,
title = {TIME-VARYING DYNAMICAL STAR FORMATION RATE},
author = {Lee, Eve J. and Chang, Philip and Murray, Norman, E-mail: evelee@berkeley.edu},
abstractNote = {We present numerical evidence of dynamic star formation in which the accreted stellar mass grows superlinearly with time, roughly as t {sup 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.},
doi = {10.1088/0004-637X/800/1/49},
journal = {Astrophysical Journal},
number = 1,
volume = 800,
place = {United States},
year = {Tue Feb 10 00:00:00 EST 2015},
month = {Tue Feb 10 00:00:00 EST 2015}
}