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Moving-mesh simulations of star-forming cores in magneto-gravo-turbulence

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Star formation in our Galaxy occurs in molecular clouds that are self-gravitating, highly turbulent, and magnetized. We study the conditions under which cloud cores inherit large-scale magnetic field morphologies and how the field is governed by cloud turbulence. We present four moving-mesh simulati...

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Main Authors: Mocz, Philip (Author) , Burkhart, Blakesley (Author) , Hernquist, Lars (Author) , McKee, Christopher F. (Author) , Springel, Volker (Author)
Format: Article (Journal)
Language:English
Published: 2017 March 20
In: The astrophysical journal
Year: 2017, Volume: 838, Issue: 1, Pages: 1-14
ISSN:1538-4357
DOI:10.3847/1538-4357/aa6475
Online Access:Verlag, kostenfrei, Volltext: http://dx.doi.org/10.3847/1538-4357/aa6475
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Author Notes:Philip Mocz, Blakesley Burkhart, Lars Hernquist, Christopher F. McKee, and Volker Springel
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Summary:Star formation in our Galaxy occurs in molecular clouds that are self-gravitating, highly turbulent, and magnetized. We study the conditions under which cloud cores inherit large-scale magnetic field morphologies and how the field is governed by cloud turbulence. We present four moving-mesh simulations of supersonic, turbulent, isothermal, self-gravitating gas with a range of magnetic mean-field strengths characterized by the Alfvénic Mach number ##IMG## [http://ej.iop.org/images/0004-637X/838/1/40/apjaa6475ieqn1.gif] $ \mathcal M _\rmA,0$ , resolving prestellar core formation from parsec to a few astronomical unit scales. In our simulations with the turbulent kinetic energy density dominating over magnetic pressure ( ##IMG## [http://ej.iop.org/images/0004-637X/838/1/40/apjaa6475ieqn2.gif] $ \mathcal M _\rmA,0\gt 1$ ), we find that the collapse is approximately isotropic with B ∝ ρ 2/3 , core properties are similar regardless of initial mean-field strength, and the field direction on 100 au scales is uncorrelated with the mean field. However, in the case of a dominant large-scale magnetic field ( ##IMG## [http://ej.iop.org/images/0004-637X/838/1/40/apjaa6475ieqn3.gif] $ \mathcal M _\rmA,0=0.35$ ), the collapse is anisotropic with B ∝ ρ 1/2 . This transition at ##IMG## [http://ej.iop.org/images/0004-637X/838/1/40/apjaa6475ieqn4.gif] $ \mathcal M _\rmA,0\sim 1$ is not expected to be sharp, but clearly signifies two different paths for magnetic field evolution in star formation. Based on observations of different star-forming regions, we conclude that star formation in the interstellar medium may occur in both regimes. Magnetic field correlation with the mean field extends to smaller scales as ##IMG## [http://ej.iop.org/images/0004-637X/838/1/40/apjaa6475ieqn5.gif] $ \mathcal M _\rmA,0$ decreases, making future Atacama Large Millimeter Array observations useful for constraining ##IMG## [http://ej.iop.org/images/0004-637X/838/1/40/apjaa6475ieqn6.gif] $ \mathcal M _\rmA,0$ of the interstellar medium.
Item Description:Gesehen am 24.10.2017
Physical Description:Online Resource
ISSN:1538-4357
DOI:10.3847/1538-4357/aa6475

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