870 micron Imaging of a Transitional Disk in Upper Scorpius: Holdover from the Era of Giant Planet Formation?

TL;DR

This study uses high-resolution 880 micron imaging to analyze a transition disk in Upper Scorpius, revealing an inner cavity likely caused by giant planets, providing insights into planet formation processes.

Contribution

First detailed millimeter imaging of this transition disk, identifying its structure and suggesting planet formation as the cause of the inner cavity.

Findings

Inner disk cavity extends from 20-70 AU.

Contains about 0.1 Jupiter masses of dust.

Likely caused by giant planets, not stellar companions.

Abstract

We present 880 micron images of the transition disk around the star [PZ99] J160421.7-213028, a solar-mass star in the nearby Upper Scorpius association. With a resolution down to 0.34 arcsec, we resolve the inner hole in this disk, and via model fitting to the visibilities and spectral energy distribution we determine both the structure of the outer region and the presence of sparse dust within the cavity. The disk contains about 0.1 Jupiter masses of mm-emitting grains, with an inner disk edge of about 70 AU. The inner cavity contains a small amount of dust with a depleted surface density in a region extending from about 20-70 AU. Taking into account prior observations indicating little to no stellar accretion, the lack of a binary companion, and the presence of dust near 0.1 AU, we determine that the most likely mechanism for the formation of this inner hole is the presence of one or more giant planets.