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Title: Driven and decaying turbulence simulations of low–mass star formation: From clumps to cores to protostars

Abstract

Molecular clouds are observed to be turbulent, but the origin of this turbulence is not well understood. As a result, there are two different approaches to simulating molecular clouds, one in which the turbulence is allowed to decay after it is initialized, and one in which it is driven. We use the adaptive mesh refinement (AMR) code, Orion, to perform high-resolution simulations of molecular cloud cores and protostars in environments with both driven and decaying turbulence. We include self-gravity, use a barotropic equation of state, and represent regions exceeding the maximum grid resolution with sink particles. We analyze the properties of bound cores such as size, shape, line width, and rotational energy, and we find reasonable agreement with observation. At high resolution the different rates of core accretion in the two cases have a significant effect on protostellar system development. Clumps forming in a decaying turbulence environment produce high-multiplicity protostellar systems with Toomre Q unstable disks that exhibit characteristics of the competitive accretion model for star formation. In contrast, cores forming in the context of continuously driven turbulence and virial equilibrium form smaller protostellar systems with fewer low-mass members. Furthermore, our simulations of driven and decaying turbulence show some statisticallymore » significant differences, particularly in the production of brown dwarfs and core rotation, but the uncertainties are large enough that we are not able to conclude whether observations favor one or the other.« less

Authors:
 [1];  [2];  [1]
  1. Univ. of California, Berkeley, CA (United States)
  2. Univ. of California, Berkeley, CA (United States); Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Publication Date:
Research Org.:
Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1248292
Report Number(s):
LLNL-JRNL-405221
Journal ID: ISSN 0004-637X
Grant/Contract Number:  
AC52-07NA27344
Resource Type:
Accepted Manuscript
Journal Name:
Astrophysical Journal
Additional Journal Information:
Journal Volume: 686; Journal Issue: 2; Journal ID: ISSN 0004-637X
Publisher:
Institute of Physics (IOP)
Country of Publication:
United States
Language:
English
Subject:
79 ASTRONOMY AND ASTROPHYSICS; ISM: clouds; stars: formation; methods: numerical; hydrodynamics; turbulence

Citation Formats

Offner, Stella S. R., Klein, Richard I., and McKee, Christopher F. Driven and decaying turbulence simulations of low–mass star formation: From clumps to cores to protostars. United States: N. p., 2008. Web. doi:10.1086/590238.
Offner, Stella S. R., Klein, Richard I., & McKee, Christopher F. Driven and decaying turbulence simulations of low–mass star formation: From clumps to cores to protostars. United States. doi:10.1086/590238.
Offner, Stella S. R., Klein, Richard I., and McKee, Christopher F. Mon . "Driven and decaying turbulence simulations of low–mass star formation: From clumps to cores to protostars". United States. doi:10.1086/590238. https://www.osti.gov/servlets/purl/1248292.
@article{osti_1248292,
title = {Driven and decaying turbulence simulations of low–mass star formation: From clumps to cores to protostars},
author = {Offner, Stella S. R. and Klein, Richard I. and McKee, Christopher F.},
abstractNote = {Molecular clouds are observed to be turbulent, but the origin of this turbulence is not well understood. As a result, there are two different approaches to simulating molecular clouds, one in which the turbulence is allowed to decay after it is initialized, and one in which it is driven. We use the adaptive mesh refinement (AMR) code, Orion, to perform high-resolution simulations of molecular cloud cores and protostars in environments with both driven and decaying turbulence. We include self-gravity, use a barotropic equation of state, and represent regions exceeding the maximum grid resolution with sink particles. We analyze the properties of bound cores such as size, shape, line width, and rotational energy, and we find reasonable agreement with observation. At high resolution the different rates of core accretion in the two cases have a significant effect on protostellar system development. Clumps forming in a decaying turbulence environment produce high-multiplicity protostellar systems with Toomre Q unstable disks that exhibit characteristics of the competitive accretion model for star formation. In contrast, cores forming in the context of continuously driven turbulence and virial equilibrium form smaller protostellar systems with fewer low-mass members. Furthermore, our simulations of driven and decaying turbulence show some statistically significant differences, particularly in the production of brown dwarfs and core rotation, but the uncertainties are large enough that we are not able to conclude whether observations favor one or the other.},
doi = {10.1086/590238},
journal = {Astrophysical Journal},
number = 2,
volume = 686,
place = {United States},
year = {2008},
month = {10}
}

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