Protoplanetary Disk Winds by Magnetorotational Instability : Formation of an Inner Hole and a Crucial Assist for Planet Formation

TL;DR

This paper demonstrates through 3D MHD simulations that MRI-driven disk winds cause inner disk clearing, influence planet formation, and exhibit observable time variability, significantly impacting protoplanetary disk evolution.

Contribution

It introduces a global model showing MRI-driven disk winds lead to inner hole formation and affect planet formation processes in protoplanetary disks.

Findings

Inner holes form due to MRI-driven winds from the inner disk regions.

Disk winds cause time-variable mass loss with quasi-periodic behavior.

Inner disk clearing suppresses boulder infall and planetary migration.

Abstract

By constructing a global model based on 3D local magnetohydrodynamical (MHD) simulations, we show that the disk wind driven by magnetorotational instability (MRI) plays a significant role in the dispersal of the gas component of proto-planetary disks. Because the mass loss time scale by the MRI-driven disk winds is proportional to the local Keplerian rotation period, a gas disk dynamically evaporates from the inner region with possibly creating a gradually expanding inner hole, while a sizable amount of the gas remains in the outer region. The disk wind is highly time-dependent with quasi-periodicity of several times Keplerian rotation period at each radius, which will be observed as time-variability of protostar-protoplanetary disk systems. These features persistently hold even if a dead zone exists because the disk winds are driven from the surface regions where ionizing cosmic rays and high energy photons can penetrate. Moreover, the predicted inside-out clearing significantly suppresses the infall of boulders to a central star and the Type I migration of proto-planets which are favorable for the formation and survival of planets.