Mechanisms determining protostellar disk size distributions

ABSTRACT :
The physical properties of protostellar disks, such as mass and size, are likely closely related to the planet formation process. Several mechanisms have been proposed to influence disk properties during star formation. To observationally examine these theories, we have been measuring disk properties and comparing them with magnetic fields, turbulence, gas kinematics, and stellar mass in various systems. In this presentation, I will summarize our observational results on the relationships between disk properties and physical conditions in protostellar sources, discuss key mechanisms determining disk properties, and demonstrate that theoretical predictions from the combination of hydrodynamics and non-ideal MHD can explain the observed size distributions.