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Abstract: We carry out three-dimensional MHD simulations of star formation inturbulent, magnetized clouds, including ambipolar diffusion and feedback fromprotostellar outflows. The calculations focus on relatively diffuse cloudsthreaded by a strong magnetic field capable of resisting severe tangling byturbulent motions and retarding global gravitational contraction in thecross-field direction. They are motivated by observations of the Taurusmolecular cloud complex and, to a lesser extent, Pipe Nebula, which shows anordered large-scale magnetic field, as well as elongated condensations that aregenerally perpendicular to the large-scale field. We find that stars form inearnest in such clouds when enough material has settled gravitationally alongthe field lines that the mass-to-flux ratios of the condensations approach thecritical value. Only a small fraction of order 1% or less of the nearlymagnetically-critical, condensed material is turned into stars per localfree-fall time, however. The slow star formation takes place in condensationsthat are moderately supersonic; it is regulated primarily by magnetic fields,rather than turbulence. The quiescent condensations are surrounded by diffusehalos that are much more turbulent, as observed in the Taurus complex. Strongsupport for magnetic regulation of star formation in this complex comes fromthe extremely slow conversion of the already condensed, relatively quiescentC$^{18}$O gas into stars, at a rate two orders of magnitude below the maximum,free-fall value. We analyze the properties of dense cores, including their massspectrum, which resembles the stellar initial mass function.

Autor: Fumitaka Nakamura Niigata Univ., Zhi-Yun Li Univ. of Virginia


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