The formation of protostellar disks in magnetized cloud cores

We use magnetic collapse models to place some constraints on the properties of a centrifugally-supported inner disk that is formed from the collapse of a magnetic core. The core represents an outer nonequilibrium flattened envelope which collapses dynamically to form a protostar and inner disk. The inner disk forms after a central protostar has formed, and grows by dynamical accretion from the envelope. We find that the centrifugal radius of the inner disk is related to its mass by the two important parameters characterizing the background medium: the background rotation rate Rb and the background magnetic field strength B-ref. To form a star-disk system of the type that is typically observed requires significant redistribution of mass and angular momentum within the inner disk. As the central star gains mass at the expense of the disk, the disk radius also increases dramatically if the total angular momentum is conserved.