Abundances of hydrogen sulfide in star-forming regions

Interstellar hydrogen sulfide (H2S) and its isotopic variant H2 34S have been observed toward several star-forming regions via their 1(10)-1(01) transitions at 2 mm, using the FCRAO telescope. In sources where both isotopic species H2S and H2 34S were observed, column densities of approximately 10(16) cm-2 were measured. Column density lower limits of approximately 10(14) cm-2 for H2S were found for other sources, where only the main isotopic line was observed. The fractional abundances of H2S relative to molecular hydrogen appear to be enhanced by at least an order of magnitude relative to quiescent cloud values (approximately 10(-9)) for many of the observed sources. Such enhancement toward star-forming clouds suggests that some process involving elevated temperature aids in producing this species; this could be gas-phase reactions, grain-related processes, or both.