Impact of Differential Dust Settling on the SED and Polarization: Application to the Inner Region of the HL Tau Disk

Document Type

Article

Publication Date

6-2-2021

Publication Title

Astrophysical Journal

Volume

913

Issue

2

First page number:

1

Last page number:

10

Abstract

The polarimetric observations of the protoplanetary disk around HL Tau have shown the scattering-induced polarization at ALMA Band 7, which indicates that the maximum dust size is ~100 μm, while the spectral energy distribution (SED) has suggested that the maximum dust size is approximately a millimeter. To solve the contradiction, we investigate the impact of differential settling of dust grains on the SED and polarization. If the disk is optically thick, a longer observing wavelength traces more interior layers, which would be dominated by larger grains. We find that the SED of the center part of the HL Tau disk can be explained with millimeter-sized grains for a broad range of turbulence strength, while 160 μm–sized grains cannot be explained unless the turbulence strength parameter αt is lower than 10−5. We also find that the observed polarization fraction can be potentially explained with a maximum dust size of 1 mm if... (See full abstract in article).

Keywords

Protoplanetary disks; Planet formation

Disciplines

Stars, Interstellar Medium and the Galaxy

Language

English

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