Scattered Light from Dust in the Cavity of the V4046 Sgr Transition Disk

TL;DR

This study uses Gemini Planet Imager observations to reveal a narrow dust ring and halo in the V4046 Sgr circumbinary disk, providing insights into planet formation processes and dust distribution within the disk cavity.

Contribution

First direct imaging of dust structures within the cavity of the V4046 Sgr transition disk using GPI, highlighting dust distribution relevant to planet formation models.

Findings

Detected a narrow ~10 AU ring of polarized near-infrared flux at ~14 AU.

Identified a faint outer halo of scattered light extending to ~45 AU.

Supported models of planet-disk interactions creating pressure traps and radial dust variations.

Abstract

We report the presence of scattered light from dust grains located in the giant planet formation region of the circumbinary disk orbiting the ~20-Myr-old close (~0.045 AU separation) binary system V4046 Sgr AB based on observations with the new Gemini Planet Imager (GPI) instrument. These GPI images probe to within ~7 AU of the central binary with linear spatial resolution of ~3 AU, and are thereby capable of revealing dust disk structure within a region corresponding to the giant planets in our solar system. The GPI imaging reveals a relatively narrow (FWHM ~10 AU) ring of polarized near-infrared flux whose brightness peaks at ~14 AU. This ~14 AU radius ring is surrounded by a fainter outer halo of scattered light extending to ~45 AU, which coincides with previously detected mm-wave thermal dust emission. The presence of small grains that efficiently scatter starlight well inside the mm-wavelength disk cavity supports current models of planet formation that suggest planet-disk interactions can generate pressure traps that impose strong radial variations in the particle size distribution throughout the disk.