3D Gap Opening in Non-Ideal MHD Protoplanetary Disks: Asymmetric Accretion, Meridional Vortices, and Observational Signatures

TL;DR

This paper investigates 3D non-ideal MHD simulations of protoplanetary disks, revealing asymmetric accretion, meridional vortices, and observational signatures that differ from previous models, with implications for planet formation and disk observations.

Contribution

It introduces self-consistent non-ideal MHD coefficients in 3D simulations, showing how magnetic flux concentration and fast accretion layers influence gap dynamics and observable kinematics.

Findings

Magnetic flux concentrates in planet-opened gaps.

Fast accretion layers significantly deplete gaps and affect planetary growth.

Meridional vortices break symmetry and impact observational signatures.

Abstract

Recent high-angular resolution ALMA observations have revealed rich information about protoplanetary disks, including ubiquitous substructures and three-dimensional gas kinematics at different emission layers. One interpretation of these observations is embedded planets. Previous 3-D planet-disk interaction studies are either based on viscous simulations, or non-ideal magnetohydrodynamics (MHD) simulations with simple prescribed magnetic diffusivities. This study investigates the dynamics of gap formation in 3-D non-ideal MHD disks using non-ideal MHD coefficients from the look-up table that is self-consistently calculated based on the thermo-chemical code. We find a concentration of the poloidal magnetic flux in the planet-opened gap (in agreement with previous work) and enhanced field-matter coupling due to gas depletion, which together enable efficient magnetic braking of the gap material, driving a fast accretion layer significantly displaced from the disk midplane. The fast accretion helps deplete the gap further and is expected to negatively impact the growth of planetary embryos. It also affects the corotation torque by shrinking the region of horseshoe orbits on the trailing side of the planet. Together with the magnetically driven disk wind, the fast accretion layer generates a large, persistent meridional vortex in the gap, which breaks the mirror symmetry of gas kinematics between the top and bottom disk surfaces. Finally, by studying the kinematics at the emission surfaces, we discuss the implications of planets in realistic non-ideal MHD disks on kinematics observations.