Imaging the Molecular Disk Orbiting the Twin Young Suns of V4046 Sgr

TL;DR

This study images the molecular disk around the young binary star V4046 Sgr, revealing its structure, mass, and orientation, which offers insights into planet formation around binary systems.

Contribution

First detailed imaging of the molecular disk around V4046 Sgr, showing its extent, mass, and coplanarity with the binary, informing planet formation theories.

Findings

Disk extends to ~370 AU

Disk mass is ~110 Earth masses in gas

Disk is coplanar with the binary system

Abstract

We have imaged the disk surrounding the nearby (D~73 pc), ~12 Myr, classical T Tauri binary system V4046 Sgr with the Submillimeter Array (SMA) at an angular resolution of ~2". We detect a rotating disk in 12CO(2-1) and 13CO(2-1) emission, and resolve the continuum emission at 1.3 mm. We infer disk gas and dust masses of ~110 and ~40 Earth masses, respectively. Fits to a power-law disk model indicate that the molecular disk extends to ~370 AU and is viewed at an inclination of between ~33 and ~39 degrees for dynamical stellar masses ranging from 1.8 $M_\odot$ down to 1.5 $M_\odot$ (the range of total mass previously determined for the central, 2.4 day spectroscopic binary). This range of disk inclination is consistent with that assumed in deducing the central binary mass (i.e., 35 degrees), suggesting that the V4046 Sgr binary system and its circumbinary, molecular disk are coplanar. In light of the system's age and binarity, the presence of an extensive molecular disk orbiting V4046 Sgr provides constraints on the timescales of processes related to Jovian planet formation, and demonstrates that circumbinary Jovian planets potentially could form around close binary systems.