The Formation and Evolution of Protostellar Disks; 3D AMR Hydro-Simulations of Collapsing, Rotating Bonnor-Ebert-Spheres

We present a detailed study of the collapse of molecular cloud cores using high resolution 3D adaptive mesh refinement (AMR) numerical simulations. In this first in a series of investigations our initial conditions consists of spherical molecular core obeying the hydrostatic Bonnor-Ebert-Profile with varying degrees of initial rotation. Our simulations cover both the formation of massive disks in which massive stars form as well as low mass disks. We use a customized version of the FLASH code whose AMR technique allows us to follow the formation of a protstellar disk and protostellar core(s) through more than ten orders in density increase while continuously resolving the local Jeans length (i.e. obeying the Truelove criterion, Truelove et al. (1997)). Our numerical simulations also incorporate the energy loss due to molecular line emission in order to obtain a more realistic picture of protostellar core and disk formation. Out initial states model system of mass 168 M_sol and 2.1 M_sol that will form high and low mass stars, respectively. We follow many features such as the development complex shock structures, and the possible fragmentation of the disk. We find that slowly rotating cores (Omega t_ff = 0.1) produce disks in which a strong bar develops but which does not fragment. Faster initial rotation rates (Omega t_ff = 0.2) result in the formation of a ring which may fragment into two star-forming cores. The size of the rings found in our simulated disks agree with the observations of similar systems.