Kengo Tomida Seminar

Abstract

Angular momentum transport is one of the key processes governing the evolution and structure of protoplanetary disks. Because protoplanetary disks are cold and dense, the gas is poorly ionized, and non-ideal magnetohydrodynamic processes play a significant role in regulating angular momentum transport.

In star and disk formation processes, the gas is primarily ionized by cosmic rays with relatively low energies. Since such cosmic rays are significantly attenuated by the gas, cosmic-ray ionization is highly non-uniform and time-dependent. Furthermore, recent observations suggest that forming protostars may be producing cosmic rays themselves.

To model this complex interaction between cosmic rays and the dynamics of star and disk formation processes, we have been developing a new simulation code. In this talk, I will review recent observations of protoplanetary disks and their ionization states, and present our recent work on modeling star formation processes, including the effects of cosmic rays.