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 most 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 has recently led to paradigm shift that disk gas dynamics and evolution is governed by magnetized disk winds. I will present recent and ongoing research work under this new framework towards a comprehensive understanding of disk physics and its long-term evolution, as well as implications to planet formation.
Intro: Prof. Xuening Bai obtained his BS in physics and mathematics from Tsinghua University in 2007, and his PhD in astrophysics from Princeton University in 2012. He was a Hubble postdoctoral fellow at 2012-2015, and an ITC (Institute for Theory and Computation) postdoctoral fellow in 2015-2017, at Harvard-Smithsonian Center for Astrophysics. He joined the faculty at Institute for Advanced Study at Tsinghua University in 2017 Fall, and is also an adjunct professor at Department of Astronomy. Prof. Bai is a theoretical and computational astrophysicist. His main research areas include protoplanetary disks and planet formation, as well as plasma astrophysics of cosmic-rays. His research primarily employs magnetohydrodynamic simulations to investigate the microphysical aspects of astrophysical systems.