Disk Winds Driven by Magnetorotational Instability and Dispersal of Proto-Planetary Disks

TL;DR

This study uses 3D MHD simulations to explore how magnetorotational instability drives structured disk winds, influencing the dispersal and dust sedimentation in proto-planetary disks.

Contribution

It demonstrates that MRI-amplified magnetic fields generate structured disk winds and excite wave fluxes, impacting disk evolution and dust sedimentation.

Findings

Magnetorotational instability amplifies magnetic fields in disks.

Structured disk winds are driven by breakup of channel flows.

Waves excited by channel flows may aid dust sedimentation.

Abstract

By performing local three-dimensional MHD simulations of stratified accretion disks, we investigate disk winds driven by MHD turbulence. Initially given weak vertical magnetic fields are effectively amplified by magnetorotational instability and winding due to differential rotation. Large scale channel flows develop most effectively at 1.5 - 2 times the scale heights where the magnetic pressure is comparable to but slightly smaller than the gas pressure. The breakup of these channel flows drives structured disk winds by transporting the Poynting flux to the gas. These features are universally observed in the simulations of various initial fields. This disk wind process should play an essential role in the dynamical evaporation of proto-planetary disks. The breakup of channel flows also excites the momentum fluxes associated with Alfvenic and (magneto-)sonic waves toward the mid-plane, which possibly contribute to the sedimentation of small dust grains in protoplanetary disks.