学术报告—Planet-Disk Interaction in Windy Disks

Abstract: 

Thanks to advanced observational instruments like ALMA, we can now probe the structure of the protoplanetary disk (PPD) where planets form. These observations unveiled distinct substructures like rings and gaps in numerous PPDs. These substructures could originate from the forming planets located within these gaps, while some could form via other mechanisms without planets. 

The evolution of rotating disks, including PPDs, is governed by the angular momentum transfer. Previous studies on planet-disk interaction assumed that the angular momentum transfers via the turbulent viscosity due to magneto-rotational instability (MRI). However, recent magneto-hydrodynamics (MHD) research suggests that the vertical removal of angular momentum through MHD-disk wind plays a dominant role, especially in weakly ionized regions where MRI is suppressed. Notably, many substructures are found in these weakly ionized outer regions of PPDs, emphasizing the need to study planet-disk interactions in the context of windy disks rather than just the conventional viscous framework. 

Building on this, we carried out 3D MHD simulations of planet-disk interaction in the windy disk. Our simulation incorporates both MRI turbulence and MHD disk wind, with the latter being more dominant. Our findings show that the planet gravity not only induces a density gap but also draws the magnetic flux to the planetary orbit. This magnetic flux concentration results in a rapid radial accretion within the planetary gap, making the gap deeper. In addition, this enhanced accretion modifies the planetary co-orbital flow, weakening the corotation torque and altering the path of gas accretion to the planet.

Bio:

Dr. Aoyama's research focuses on planet formation, particularly the formation of giant planets. He studied at the University of Tokyo and received his bachelor's degree in 2014, master's in 2016, and Ph.D. in 2019. After his doctoral studies, Dr. Aoyama joined the Institute for Advanced Study at Tsinghua University as a postdoctoral researcher until 2022. Then, he moved to the Kavli Institute for Astronomy and Astrophysics at Peking University in 2022, where he currently continues his postdoctoral research.