磁場と超音速乱流に支配された星間ガスの自己重力分裂 : 3次元数値シミュレーション(宇宙・惑星(4),一般講演)

概要

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We demonstrate that the formation of collapsing self-gravitating cores in subcritical clouds is accelerated by nonlinear flows, by performing three-dimensional nonideal MHD simulations. Magnetic ambipolar diffusion occurs very rapidly initially due to the sharp gradients introduced by the initial random supersonic (and trans-Alfvenic) turbulent flow. It subsequently occurs more slowly in the traditional near-quasi-static manner, but in regions of greater mean density than present in the initial state. The overall timescale for runaway growth of the first core(s) is several ×10^6yr, even though previous studies have found a timescale of several ×10^7yr when starting with linear perturbations and similar physical parameters.
2008-09-04