2019ApJ...871..141Q

Reaching a length of 10 pc projected in the plane of the sky, the radio jet associated with Herbig-Haro (HH) objects 80 and 81 (HH 80-81) is known to be the largest and best collimated protostellar jet in our Galaxy. The nature of the molecular outflow associated with this extraordinary jet remains an unsolved question, and is of great interest for our understanding of the relationship between jets and outflows in high-mass star formation. Here we present Atacama Pathfinder EXperiment CO (6-5) and (7-6), James Clerk Maxwell Telescope CO (3-2), Caltech Submillimeter Observatory CO (2-1), and Submillimeter Array CO and ¹³CO (2-1) mapping observations of the outflow. We report on the detection of a two-component outflow consisting of a collimated component along the jet path and a wide-angle component with an opening angle of about 30°. The gas velocity structure suggests that each of the two components traces part of a primary wind. From large velocity gradient calculations of the CO lines, the outflowing gas has a temperature around 88 K, indicating that it is being heated by shocks. Based on the CO (6-5) data, the outflow mass is estimated to be a few M_☉, dominated by the wide-angle component. A comparison between the HH 80-81 outflow and other well shaped massive outflows suggests that the opening angle of massive outflows continues to increase over time. Therefore, the mass-loss process in the formation of early-B stars seems to be similar to that in low-mass star formation, except that a jet component would disappear as the central source evolved to an ultracompact H II region.