Unified Models of Molecular Emission from Class 0 Protostellar Outflow Sources

TL;DR

This study applies a unified, realistic physical model to molecular emission data from three Class 0 protostars, revealing consistent gas properties and chemical abundance variations due to dynamical processes.

Contribution

It demonstrates the applicability of a single infall/outflow model to multiple protostars and derives their physical and chemical parameters using 3D radiative transfer modeling.

Findings

Molecular gas abundances are reduced in infalling envelopes due to freeze-out.

Abundances are enhanced in outflows, likely from dynamical activity.

Physical parameters are similar across different sources despite line profile variations.

Abstract

Low mass star-forming regions are more complex than the simple spherically symmetric approximation that is often assumed. We apply a more realistic infall/outflow physical model to molecular/continuum observations of three late Class 0 protostellar sources with the aims of (a) proving the applicability of a single physical model for all three sources, and (b) deriving physical parameters for the molecular gas component in each of the sources. We have observed several molecular species in multiple rotational transitions. The observed line profiles were modelled in the context of a dynamical model which incorporates infall and bipolar outflows, using a three dimensional radiative transfer code. This results in constraints on the physical parameters and chemical abundances in each source. Self-consistent fits to each source are obtained. We constrain the characteristics of the molecular gas in the envelopes as well as in the molecular outflows. We find that the molecular gas abundances in the infalling envelope are reduced, presumably due to freeze-out, whilst the abundances in the molecular outflows are enhanced, presumably due to dynamical activity. Despite the fact that the line profiles show significant source-to-source variation, which primarily derives from variations in the outflow viewing angle, the physical parameters of the gas are found to be similar in each core.