The Extremely High-Velocity Outflow from the Luminous Young Stellar Object G5.89-0.39

TL;DR

This study images and analyzes extremely high-velocity outflows from the young stellar object G5.89-0.39, revealing multiple lobes, a Hubble-like velocity structure, and a temperature increase with velocity, supporting a jet-driven bow shock model.

Contribution

First detailed imaging of high-velocity outflows in G5.89-0.39 with temperature-velocity correlation and kinematic structure analysis.

Findings

Multiple outflow lobes identified with N-S and NW-SE orientations.

Outflow gas temperature increases with velocity.

Observational features support jet-driven bow shock model.

Abstract

We have imaged the extremely high-velocity outflowing gas in CO (2-1) and (3-2) associated with the shell-like ultracompact HII region G5.89-0.39 at a resolution of ~3" (corresponding to ~4000 AU) with the Submillimeter Array. The integrated high-velocity (>45 km/s) CO emission reveals at least three blueshifted lobes and two redshifted lobes. These lobes belong to two outflows, one oriented N-S, the other NW-SE. The NW-SE outflow is likely identical to the previously detected Br_gamma outflow. Furthermore, these outflow lobes all clearly show a Hubble-like kinematic structure. For the first time, we estimate the temperature of the outflowing gas as a function of velocity with the large velocity gradient calculations. Our results reveal a clear increasing trend of temperature with gas velocity. The observational features of the extremely high-velocity gas associated with G5.89-0.39 qualitatively favor the jet-driven bow shock model.