Collapse of Magnetized Molecular Cloud Cores. II. Numerical Results

In a previous paper (Paper I) we presented a perturbative analysis of the collapse of a molecular cloud core threaded by an ordered magnetic field, obtaining a semianalytical solution applicable over a moderate range of temporal and spatial scales. In the present paper we supplement this analysis with a numerical solution of the magnetohydrodynamic (MHD) equations that include the effects of ambipolar diffusion, valid in the region where magnetic effects dominate the dynamics of the collapse. We focus on the formation of a flattened disequilibrium structure (pseudodisk) around the central protostar. The numerical solution gives dimensionless values for the radius of the pseudodisk as a function of time