Resolved images of the protoplanetary disk around HD 100546 with ALMA

TL;DR

This paper presents the first resolved ALMA images of the protoplanetary disk around HD 100546, revealing a compact, asymmetric dust disk and an extended gas disk, providing insights into planet formation processes.

Contribution

First resolved millimeter images of HD 100546's disk showing a truncated dust disk and extended gas, highlighting radial drift and potential planet formation signatures.

Findings

Gas disk extends to 350 au

Dust emission is compact (<60 au) and asymmetric

Radial drift explains lack of large particles outside 60 au

Abstract

The disk around the Herbig Ae/Be star HD 100546 has been extensively studied and it is one of the systems for which there are observational indications of ongoing and/or recent planet formation. However, up until now no resolved image of the millimeter dust emission or the gas has been published. We present the first resolved images of the disk around HD 100546 obtained in Band 7 with the ALMA observatory. The CO (3-2) image reveals a gas disk that extends out to 350 au radius at the 3-sigma level. Surprisingly, the 870um dust continuum emission is compact (radius <60 au) and asymmetric. The dust emission is well matched by a truncated disk with outer radius of $\approx$50 au. The lack of millimeter-sized particles outside the 60 au is consistent with radial drift of particles of this size. The protoplanet candidate, identified in previous high-contrast NACO/VLT L' observations, could be related to the sharp outer edge of the millimeter-sized particles. Future higher angular resolution ALMA observations are needed to determine the detailed properties of the millimeter emission and the gas kinematics in the inner region (<2arcsec). Such observations could also reveal the presence of a planet through the detection of circumplanetary disk material.