Dust Dynamics in Protoplanetary Disk Winds Driven by Magneto-Rotational Turbulence: A Mechanism for Floating Dust Grains with Characteristic Sizes

TL;DR

This study models dust grain behavior in protoplanetary disk winds driven by magnetorotational turbulence, revealing how different grain sizes distribute vertically and their potential observational signatures.

Contribution

It provides a detailed simulation of dust dynamics across grain sizes in magnetorotationally turbulent disks, highlighting the floating of intermediate-sized grains and their spatial distribution.

Findings

Small grains are dragged upward with gas flow.

Intermediate grains float at several scale heights.

Distribution varies with distance from the star.

Abstract

We investigate the dynamics of dust grains with various sizes in protoplanetary disk winds driven by magnetorotational turbulence, by simulating the time evolution of the dust grain distribution in the vertical direction. Small dust grains, which are well coupled to the gas, are dragged upward with the upflowing gas, while large grains remain near the midplane of a disk. Intermediate--size grains float at several scale heights from the midplane in time-averated force balance between the downward gravity and the upward gas drag. For the minimum mass solar nebula at 1 AU, dust grains with size of 20 -- 40 $\mu m$ float at 5-10 scale heights from the midplane. Considering the dependence on the distance from the central star, smaller-size grains remain only in an outer region of the disk, while larger-size grains are distributed in a broader region. We also discuss the implication of our result to the observation of dusty material around young stellar objects.