Kinematics of a hot massive accretion disk candidate

TL;DR

This study uses high-resolution radio observations to analyze a candidate massive accretion disk around a high-mass protostar, revealing rotation, potential infall, and a jet, contributing to understanding massive star formation.

Contribution

It provides detailed kinematic analysis of a massive disk candidate, including evidence of rotation, infall, and a jet, with high angular resolution observations.

Findings

Detected velocity gradient indicating rotation perpendicular to outflow

Estimated protostar-disk mass comparable to the protostar mass

Identified a central ionized jet perpendicular to the disk

Abstract

Characterizing rotation, infall and accretion disks around high-mass protostars is an important topic in massive star formation research. With the Australia Telescope Compact Array and the Very Large Array we studied a massive disk candidate at high angular resolution in ammonia (NH3(4,4) & (5,5)) tracing the warm disk but not the envelope. The observations resolved at ~0.4'' resolution (corresponding to ~1400AU) a velocity gradient indicative of rotation perpendicular to the molecular outflow. Assuming a Keplerian accretion disk, the estimated protostar-disk mass would be high, similar to the protostellar mass. Furthermore, the position-velocity diagram exhibits additional deviation from a Keplerian rotation profile which may be caused by infalling gas and/or a self-gravitating disk. Moreover, a large fraction of the rotating gas is at temperatures >100K, markedly different to typical low-mass accretion disks. In addition, we resolve a central double-lobe cm continuum structure perpendicular to the rotation. We identify this with an ionized, optically thick jet.