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Magnetic Fields in Molecular Clouds

Published online by Cambridge University Press:  12 August 2011

Paolo Padoan
Affiliation:
ICREA & ICC, University of Barcelona, Marti i Franquès 1, E-08028 Barcelona, Spain email: ppadoan@icc.ub.edu
Tuomas Lunttila
Affiliation:
Department of Physics, University of Helsinki, Helsinki, Finland
Mika Juvela
Affiliation:
Department of Physics, University of Helsinki, Helsinki, Finland
Åke Nordlund
Affiliation:
Niels Bohr Institute, University of Copenhagen, Denmark
David Collins
Affiliation:
CASS / Department of Physics, University of California, San Diego, USA
Alexei Kritsuk
Affiliation:
CASS / Department of Physics, University of California, San Diego, USA
Michael Normal
Affiliation:
CASS / Department of Physics, University of California, San Diego, USA
Sergey Ustyugov
Affiliation:
Keldysh Institute of Applied Mathematics, Russian Academy of Sciences, Moscow, Russia
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Abstract

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Supersonic magneto-hydrodynamic (MHD) turbulence in molecular clouds (MCs) plays an important role in the process of star formation. The effect of the turbulence on the cloud fragmentation process depends on the magnetic field strength. In this work we discuss the idea that the turbulence is super-Alfvénic, at least with respect to the cloud mean magnetic field. We argue that MCs are likely to be born super-Alfvénic. We then support this scenario based on a recent simulation of the large-scale warm interstellar medium turbulence. Using small-scale isothermal MHD turbulence simulation, we also show that MCs may remain super-Alfvénic even with respect to their rms magnetic field strength, amplified by the turbulence. Finally, we briefly discuss the comparison with the observations, suggesting that super-Alfvénic turbulence successfully reproduces the Zeeman measurements of the magnetic field strength in dense MC clouds.

Type
Contributed Papers
Copyright
Copyright © International Astronomical Union 2011

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