Star Formation Signatures in the Condensation Downstream of HH 80N

Abstract

HH 80 North (hereafter HH 80N) is one of the Herbig-Haro objects associated with quiescent dense clumps. We report CO and CS BIMA observations that reveal star formation within the HH 80N dense clump. The CO emission clearly reveals a bipolar molecular outflow centered on the dense clump. The CS emission traces a ringlike structure of radius 0.24 pc. The CS kinematics shows that the ring is collapsing with an infall speed of ~0.6 km s-1. The required mass to produce the collapse is in agreement with previous ammonia observations of the 20 M☉ core, which is embedded within the CS structure. However, we cannot discard that the ring structure, driven by protostellar winds, is expanding if the CS abundance is unusually high and if the CO momentum rate is much higher than that measured because of inclination and optical depth effects. The properties of the molecular outflow and of the dense core suggest that it harbors a Class 0 object. There are also signatures of the interaction of the HH 80/81/80N outflow with the dense gas. In particular, it is possible that the HH 80/81/80N outflow has triggered or at least sped up the star formation in this region.