2004/10/21 by N. Marcelino, J. Cernicharo, E. Roueff +2 · 1 citation
Physics and Astronomy · #Astro and Planetary Science #Astrophysics and Star Formation Studies #Stellar, planetary, and galactic studies #astro-ph
paper · pdf · doi:10.1086/426934
published as Astrophys.J. 620 (2005) 308-320 · 33 pages, 6 figures, accepted for publication in ApJ
arxiv created 2004/10/21 · openalex publication_date 2005/02/09 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/07/31
We present observations of the singly and doubly deuterated species of thioformaldehyde, HDCS and D 2 CS, toward the dark cloud Barnard 1. This is the first detection of D 2 CS in space and in dense, cold prestellar regions. Column densities obtained using rotational diagrams and a large velocity gradient model show an extremely high D enhancement in thioformaldehyde in Barnard 1. Although the column density of H 2 CS is smaller than that of H 2 CO, both species show similar D enhancements in their singly and doubly deuterated species. A chemical model—including multiply deuterated species—has been used in order to interpret the observations. Predicted rotational frequencies from laboratory data for HDCS and D 2 CS are significantly in error when compared to the observed frequencies in space. Consequently, we have derived new rotational constants for these two species and for H 2 CS and H 2 C 34 S using the observed frequencies in Barnard 1. The new rotational constants allow us to predict the rotational transitions of these species with the accuracy needed for the narrow line emerging from dark clouds. Rotational constants for HDCS and D 2 CS have been obtained from the observed transitions in the laboratory and in space.