Princeton University Star Formation/ISM Rendezvous (SFIR) - Location is Rm. 140

Star formation in our Galaxy occurs in molecular clouds that are self-gravitating, highly turbulent, and magnetized. We study the conditions out of which collapse of pre-stellar cores occurs in such an environment, and how collapse proceeds from parsec to AU scale, as a function of mean magnetic field strength characterized by the Alfvenic Mach number of the mean-field M_A0. Supersonic isothermal turbulence creates a network of dense shocks with M_s^2 density jumps and exponential atmospheres balancing the ram-pressure of material being swept up. These rare and dense regions of a turbulent medium can be Jeans unstable and collapse into cores. There are two regimes of collapse based on whether the turbulent kinetic energy density dominates over the magnetic pressure of the mean-field (M_A0>1) or vice-versa (M_A0<1). In the weak-field case (M_A0>1), shocks are randomly oriented with respect to the mean field and collapse is approximately isotropic with B~rho^{2/3}, and core properties are similar regardless of initial mean-field strength. In the case of strong magnetic field (M_A0<1), dense structures are initially parallel to the magnetic field lines and collapse is anisotropic with B~rho^{1/2}, and fast turbulent reconnection diffusion is critical to remove magnetic flux and allow collapse. Magnetic field topology as a function of length scale can be used to recover key physical parameters of turbulence in the interstellar medium.