Modeling the arc and ring structures in the HD 143006 disk

TL;DR

This study models the complex dust ring and arc structures in the HD 143006 protoplanetary disk using radiative transfer simulations, revealing dust trapping and potential gravitational instability.

Contribution

It introduces a detailed 3D radiative transfer model of the HD 143006 disk with a misaligned inner disk, providing insights into dust distribution and stability.

Findings

Dust temperature discontinuity at misalignment boundary

Dust mass in the arc constitutes nearly 20% of total dust mass

Arc is close to gravitational instability with Q~1.3

Abstract

Rings and asymmetries in protoplanetary disks are considered as signposts of ongoing planet formation. In this work, we conduct three-dimensional radiative transfer simulations to model the intriguing disk around HD 143006 that has three dust rings and a bright arc. A complex geometric configuration, with a misaligned inner disk, is assumed to account for the asymmetric structures. The two-dimensional surface density is constructed by iteratively fitting the ALMA data. We find that the dust temperature displays a notable discontinuity at the boundary of the misalignment. The ring masses range from 0.6 to 16Mearth that are systematically lower than those inferred in the younger HL Tau disk. The arc occupies nearly 20% of the total dust mass. Such a high mass fraction of dust grains concentrated in a local region is consistent with the mechanism of dust trapping into vortices. Assuming a gas-to-dust mass ratio of 30 that is constant throughout the disk, the dense and cold arc is close to the threshold of being gravitationally unstable, with the Toomre parameter Q~1.3. Nevertheless, our estimate of Q relies on the assumption for the unknown gas-to-dust mass ratio. Adopting a lower gas-to-dust mass ratio would increase the inferred Q value. Follow-up high resolution observations of dust and gas lines are needed to clarify the origin of the substructures.