Thioformaldehyde Emission from the Massive Star-Forming Region DR21(OH)

TL;DR

This paper investigates thioformaldehyde (H2CS) emission in star-forming regions to develop it as a probe for temperature and density in molecular clouds, using observations and modeling of specific molecular transitions.

Contribution

It introduces the use of H2CS transitions as thermometers and densitometers for warm dense cores, expanding tools for studying star-forming regions.

Findings

H2CS transitions can effectively constrain temperature and density.

Modeling of H2CS emission reveals conditions in star-forming cores.

H2CS is a promising molecule for probing physical conditions in molecular clouds.

Abstract

Using arguments parallel to those used in support of using H2CO as a sensitive probe of temperature and density in molecular clouds, we measured the J=7-6 and J=10-9 transitions of thioformaldehyde (H2CS) in several hot core sources. The goal here was to investigate more closely the conditions giving rise to H2CS emission in cloud cores containing young stars by modelling several transitions. The H2CS molecule is a slightly asymmetric rotor, a heavier analogue to H2CO. As in H2CO, transitions occur closely spaced in frequency, though they are substantially separated in energy. Transitions of H2CS originating from the K=0, 1, 2, 3, and 4 ladders in the 230 and 345 GHz windows can productively be used to constrain densities and temperatures. As a first step in developing the use of these transitions as thermometers and densitometers, we surveyed and modeled the emission from well known warm dense cores.