Formation and Collapse of Nonaxisymmetric Protostellar Cores in Planar Magnetic Molecular Clouds

We extend our earlier work on ambipolar diffusion induced formation ofprotostellar cores in isothermal sheet-like magnetic interstellar clouds, bystudying nonaxisymmetric collapse for the physically interesting regime ofmagnetically critical and supercritical model clouds ($\mui \geq 1$, where$\mui$ is the initial mass-to-magnetic flux ratio in units of the criticalvalue for gravitational collapse). Cores that form in model simulations areeffectively triaxial, with shapes that are typically closer to being oblate,rather than prolate. Infall velocities in the critical model ($\mui = 1$) aresubsonic; in contrast, a supercritical model ($\mui = 2$) has extendedsupersonic infall that may be excluded by observations. For the magneticallycritical model, ambipolar diffusion forms cores that are supercritical ($\muc >1$) and embedded within subcritical envelopes ($\muenv < 1$). Cores in ourmodels have density profiles that eventually merge into a near-uniformbackground, which is suggestive of observed properties of cloud cores.Comment: 10 pages, 5 figures, aastex, accepted by ApJ Letter