# Publication: Three-dimensional simulations of molecular cloud fragmentation regulated by magnetic fields and ambipolar diffusion

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Title Three-dimensional simulations of molecular cloud fragmentation regulated by magnetic fields and ambipolar diffusion
Authors/Editors* T. Kudoh, S. Basu, Y. Ogata, T. Yabe
Where published* Monthly Notices of the Royal Astronomical Society
How published* Journal
Year* 2007
Volume 380
Number 499
Pages 7
Publisher
Keywords
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 infall speeds on to cores are subsonic in the case of an initially subcritical cloud, while an extended ($\ga 0.1$ 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 ($\rho$) 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 relations tend to $B \propto \rho^{0.5}$.