THE FORMATION AND INITIAL EVOLUTION OF PROTOSTELLAR DISKS

We consider the formation and evolution of an accretion disk formed during the collapse of a rotating cloud core. We take into account the effect of the usual "turbulent" α-viscosity as well as the effective viscosity due to self-gravitation in the disk. For observed values of the cloud's initial rotation rates, and for reasonable estimates of the efficiency of the various processes, we find that the disks so formed are large (radii several hundred to a few thousand a.u.), relatively massive (comparable in mass to the central star), and long-lived (tens of infall time scales).