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

摘要

We analyze radio continuum and line observations from the archives of the Very Large Array (VLA), as well as X-ray observations from the Chandra archive of the region of massive star formation W75N. Five radio continuum sources are detected: VLA1, VLA2, VLA3, Bc, and VLA4. VLA3 appears to be a radio jet; we detect J = 1-0, v = 0 SiO emission toward 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 VLA3 jet source. VLA4 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 VLA1, VLA2, and VLA3. Finally, the 2-10keV emission seen in the Chandra/ACIS image shows two regions that could be the termination shocks of the outflows from the multiple sources observed in W75N.