ALMA Observations of the T Tauri Binary System AS 205: Evidence for Molecular Winds and/or Binary Interactions

TL;DR

This paper presents high-resolution ALMA observations of the T Tauri binary system AS 205, revealing deviations from Keplerian motion in the gas disks that suggest the presence of molecular winds, binary interactions, or both.

Contribution

It provides new high-resolution millimeter observations showing deviations from Keplerian rotation, supporting hypotheses of disk winds and binary interactions in the system.

Findings

Detection of extended 12CO emission up to 2 arcsec from AS 205N.

Significant deviations from Keplerian rotation in gas disks around both stars.

Evidence supporting tidal interactions and/or molecular winds as causes.

Abstract

In this study, we present high-resolution millimeter observations of the dust and gas disk of the T Tauri star AS 205 N and its companion, AS 205 S, obtained with the Atacama Large Millimeter Array. The gas disk around AS 205 N, for which infrared emission spectroscopy demonstrates significant deviations from Keplerian motion that has been interpreted as evidence for a disk wind (Pontoppidan et al. 2011; Bast et al. 2011), also displays significant deviations from Keplerian disk emission in the observations presented here. Detections near both AS 205 N and S are obtained in 1.3 mm continuum, 12CO 2-1, 13CO 2-1 and C18O 2-1. The 12CO emission is extended up to 2 arcsec from AS 205N, and both 12CO and 13CO display deviations from Keplerian rotation at all angular scales. Two possible explanations for these observations hold up best to close scrutiny - tidal interaction with AS 205 S or disk winds (or a combination of the two), and we discuss these possibilities in some detail.