THE [HNCS]/[HSCN] RATIO IN SGRB2 AND TMC-1
Ohio State University
The formation of the metastable isomer pair, HNCS and HSCN, has been investigated in the warm molecular cloud SgrB2 and the dense cold core TMC-1. In Sagitarius B2, the $8_0_,_8$--$7_0_,_7$ and $9_0_,_9$--$8_0_,_8$ transitions of both isomers have been mapped over a $5 * 3$ region around the central hot core SgrB2(M), using the Arizona Radio Observatory (ARO) 12m telescope. In TMC-1, the $8_0_,_8$--$7_0_,_7$ and $7_0_,_7$--$6_0_,_6$ lines of both isomers have been detected. Both molecules show extended emission across SgrB2 with a ratio [HNCS]/[HSCN] $~ 1-10$. In TMC-1, the ratio is $~ 1$. The high abundance of the metastable isomer HSCN relative to HNCS suggests that the main production route to both molecules is electron recombination from the ionic precursor HNCSH+, in analogy to HCN and HNC.
Author Institution: Department of Chemistry, Steward Observatory, University of Arizona; Tucson