Three-dimensional simulations of molecular cloud fragmentation regulated by magnetic fields and ambipolar diffusion |
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| Authors: | Takahiro Kudoh Shantanu Basu Youichi Ogata Takashi Yabe |
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| Institution: | Division of Theoretical Astronomy, National Astronomical Observatory of Japan, Mitaka, Tokyo 181-8588, Japan;Department of Physics and Astronomy, University of Western Ontario, London, Ontario, Canada N6A 3K7;Department of Mechanical Engineering and Science, Tokyo Institute of Technology, O-okayama, Meguro-ku, Tokyo 152-8552, Japan;Integrated Research Institute, Solutions Research Organization, Tokyo Institute of Technology, O-okayama, Meguro-ku, Tokyo 152-8552, Japan |
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| Abstract: | We employ the first fully three-dimensional simulation to study the role of magnetic fields and ion–neutral friction in regulating gravitationally driven fragmentation of molecular clouds. The cores in an initially subcritical cloud develop gradually over an ambipolar diffusion time while the cores in an initially supercritical cloud develop in a dynamical time. The infalling speeds on to cores are subsonic in the case of an initially subcritical cloud, while an extended (≳0.1 pc) region of supersonic infall exists in the case of an initially supercritical cloud. These results are consistent with previous two-dimensional simulations. We also found that a snapshot of the relation between density (ρ) and the strength of the magnetic field ( B ) at different spatial points of the cloud coincides with the evolutionary track of an individual core. When the density becomes large, both the relations tend to B ∝ρ0.5 . |
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| Keywords: | MHD instabilities stars: formation ISM: clouds ISM: magnetic fields ISM: molecules |
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