HH 175: A Giant HH Flow Emanating From A Multiple Protostar

TL;DR

HH 175 is a large bipolar Herbig-Haro flow driven by a multiple protostar, with detailed imaging revealing its structure, origin, and interaction with surrounding cloud material in the lambda Ori region.

Contribution

This study provides detailed imaging and analysis of HH 175, revealing its origin from a multiple protostar and its interaction with the surrounding cloud, which was not previously understood.

Findings

HH 175 is a 1.65 pc bipolar outflow from a multiple protostar.

The outflow interacts with the B35 cloud, causing cloud fragmentation.

The embedded source likely formed due to compression by an ionization-shock front.

Abstract

HH 175 is an isolated Herbig-Haro object seen towards the B35 cloud in the lambda Ori region. We use deep Subaru 8m interference filter images and Spitzer images to show that HH 175 is a terminal shock in a large collimated outflow from the nearby embedded source IRAS 05417+0907. The body of the eastern outflow lobe is hidden by a dense ridge of gas. The western outflow breaks out of the front of the cometary-shaped B35 cloud, carrying cloud fragments along, which are optically visible due to photoionization by the massive lambda Ori stars. The total extent of the bipolar outflow is 13.7 arcmin, which at the adopted distance of 415 pc corresponds to a projected dimension of 1.65 pc. The embedded source IRAS 05417+0907 is located on the flow axis approximately midway between the two lobes, and near-infrared images show it to be a multiple system of 6 sources, with a total luminosity of 31 Lsun. Millimeter maps in CO, 13CO, and C18O show that the B35 cloud is highly structured with multiple cores, of which the one that spawned IRAS 05417+0907 is located at the apex of B35. It is likely that the embedded source is the result of compression by an ionization-shock front driven by the lambda Ori OB stars.