A bright radio HH object with large proper motions in the massive star-forming region W75N

TL;DR

This study combines radio and X-ray observations to identify a bright radio Herbig-Haro object with large proper motions in W75N, revealing new insights into the outflows and jet activity in this massive star-forming region.

Contribution

It provides the first evidence that the radio source Bc is a Herbig-Haro object powered by the VLA 3 jet, and reports the discovery of a new radio component VLA 4 in W75N.

Findings

VLA 3 is a radio jet with associated SiO emission.

Source Bc is a bright Herbig-Haro object, not an independent star.

Two potential outflow termination shocks are identified in X-ray data.

Abstract

We analyze radio continuum and line observations from the archives of the Very Large Array, as well as X-ray observations from the \emph{Chandra} archive of the region of massive star formation W75N. Five radio continuum sources are detected: VLA 1, VLA 2, VLA 3, Bc, and VLA 4. VLA 3 appears to be a radio jet; we detect J=1-0, v=0 SiO emission towards it, probably tracing the inner parts of a molecular outflow. The radio continuum source Bc, previously believed to be tracing an independent star, is found to exhibit important changes in total flux density, morphology, and position. These results suggest that source Bc is actually a radio Herbig-Haro object, one of the brightest known, powered by the VLA~3 jet source. VLA 4 is a new radio continuum component, located a few arcsec to the south of the group of previously known radio sources. Strong and broad (1,1) and (2,2) ammonia emission is detected from the region containing the radio sources VLA~1, VLA~2, and VLA~3. Finally, the 2-10 keV emission seen in the \emph{Chandra}/ACIS image shows two regions that could be the termination shocks of the outflows from the multiple sources observed in W75N.