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H.A.T. Vanhala (Arizona State University)
We investigate the stability of molecular cloud cores against gravitational collapse by performing three-dimensional smoothed particle hydrodynamics simulations. We assume the cores to have formed via ambipolar diffusion without outside interference and to be spherically symmetric systems joined smoothly to the background molecular cloud at the beginning of the calculations. The cores are supported against their self-gravity by rotational, thermal and magnetic support. The code employs realistic thermodynamics and includes gas cooling due to atoms, molecules and dust. The effect of a fully tangled, frozen-in magnetic field is included through magnetic pressure terms. For fixed values of rotation speed and magnetic field strength, the mass of the molecular cloud core is varied to determine the point at which the core becomes unstable. The properties of the forming protostellar disk can then be determined as a function of initial conditions. At higher rotational speeds the collapse can result in fragmentation of the collapsing core.
This work was supported by NASA Origins of Solar Systems and Astrophysics Theory Program grants.