Comparison of the dust and gas radial structure in the transition disk [PZ99] J160421.7-213028

TL;DR

This study uses ALMA observations to compare dust and gas structures in a transition disk, revealing significant differences in cavity sizes that support models involving planet-disk interactions and dust evolution.

Contribution

First detailed ALMA analysis of dust and gas radial structures in a transition disk, highlighting the impact of planet formation processes.

Findings

Dust is concentrated in an annulus between 79-114 AU.

Gas cavity radius is smaller, at about 31 AU.

Dust and gas cavities are significantly separated, supporting pressure trap models.

Abstract

We present ALMA observations of the 880um continuum and CO J= 3-2 line emission from the transition disk around [PZ99] J160421.7-213028, a solar mass star in the Upper Scorpius OB association. Analysis of the continuum data indicates that 80% of the dust mass is concentrated in an annulus extending between 79 and 114AU in radius. Dust is robustly detected inside the annulus, at a mass surface density 100 times lower than that at 80 AU. The CO emission in the inner disk also shows a significantly decreased mass surface density, but we infer a cavity radius of only 31AU for the gas. The large separation of the dust and gas cavity edges, as well as the high radial concentration of millimeter-sized dust grains, is qualitatively consistent with the predictions of pressure trap models that include hydrodynamical disk-planet interactions and dust coagulation/fragmentation processes.