Title: Towards Realistic Understandings of Protoplanetary Disks

Speaker Xuening Bai (Harvard-Smithsonian Center for Astrophysics)

Abstract:
Planet formation takes place in gas-rich protoplanetary disks (PPDs) orbiting newly born stars. The internal density and flow structures of PPDs, as well as their long-term evolution, play a crucial role in almost all stages of planet formation, yet they are far from being well understood largely due to the complex interplay among various microphysical processes. I will review the basic physical processes in PPDs that govern disk structure and evolution, highlighting the fundamental role of disk ionization and magnetic fields, described by non-ideal magnetohydrodynamic (MHD) effects. Incorporating these processes, I will first discuss previous local disk simulations that led to a paradigm shift in understanding PPD gas dynamics, as well as their limitations. I will then present global simulations of PPDs aiming to incorporate most realistic disk microphysics, which demonstrate unusual flow structures with major implications on planet formation. I will also discuss previous, ! ongoing and future observations to compare and validate these simulation results.