The molecular emission of the irradiated star forming core ahead of HH 80N

TL;DR

This study uses molecular observations to analyze the structure and chemistry of a star-forming core near HH 80N, revealing a molecular ring, depletion zones, and UV irradiation effects from nearby HH objects.

Contribution

First detailed molecular survey of the HH 80N star-forming core, identifying a ring-like structure and chemical differentiation influenced by UV irradiation.

Findings

Detection of a molecular ring structure around the core

Evidence of molecular depletion in the inner core regions

UV irradiation from HH 80N affects molecular abundances

Abstract

We present a Berkeley-Illinois-Maryland Association (BIMA) Array molecular survey of the star forming core ahead of HH 80N, the optically obscured northern counterpart of the Herbig-Haro objects HH 80/81. Continuum emission at 1.4 mm and 8 micron is detected at the center of the core, which confirms the presence of an embedded very young stellar object in the core. All detected molecular species arise in a ring-like structure, which is most clearly traced by CS(2-1) emission. This molecular ring suggests that strong molecular depletion occurs in the inner part of the core (at a radius of ~0.1 pc and densities higher than ~5 x 10^4 cm^{-3}). Despite of the overall morphology and kinematic similarity between the different species, there is significant molecular differentiation along the ring-like structure. The analysis of the chemistry along the core shows that part of this differentiation may be caused by the UV irradiation of the nearby HH 80N object, that illuminates the part of the core facing HH 80N, which results in an abundance enhancement of some of the detected species.