2001ApJ...562..842B

We extend our previous calculations of the self-gravitational collapse of an initially sheetlike, nonrotating cloud to include rotation at a wide range of initial rates (10^–15 to 10^–13 rad.s^–1). The 1 M_☉ clouds begin in hydrostatic equilibrium, appropriate for a spherical portion of an isothermal, infinite, self-gravitating flat layer, with symmetry about the midplane. Rotation is assumed to be about an axis perpendicular to the flat layer, allowing the calculations to retain axisymmetry about the rotation axis. The clouds are assumed to remain isothermal during the collapse phase that eventually results from the marginally unstable initial conditions. We find that large-scale infall motions build up during the first several free-fall times of evolution prior to the onset of the dynamic collapse phase, leading to subsonic inward-directed motions throughout the sheet, peaking at speeds of ∼0.1 km.s^–1 at radii of ∼2000 AU. The spherically averaged radial density profile of the cloud strongly resembles a Bonnor-Ebert sphere prior to this time, with a density contrast less than the critical ratio prior to the onset of collapse. We also find that rotating sheets collapse to form central protostars surrounded by infalling large-scale disklike envelopes, with surface density profiles σ∝r^–1/2.