Isotopic abundances in interstellar carbon monosulfide.
Abstract
Results are reported for measurements of the relative isotopic abundances of carbon and sulfur in interstellar carbon monosulfide, which were made by observing the 2-mm rotational-line emission from (C-13)(S-32) and (C-12)(S-34) in five dense interstellar clouds: Sgr B, W51, Orion A, M17, and NGC 2264. For each cloud, the (C-13)(S-32)/(C-12)(S-34) intensity ratio is derived at the 3-sigma level by integrating over the velocity range where the (C-12)(S-34) intensity is greater than half its peak value. All the intensity ratios are found to be larger than the terrestrial abundance ratio, but measurements of the (C-12)(S-33)/(C-12)(S-34) intensity ratio in Sgr B and Orion A are not found to be significantly different from the terrestrial value. It is concluded that the data seem to indicate a source-to-source variation of the relative isotopic abundance in CS, and that the results are consistent with an approximately terrestrial value for the interstellar sulfur isotopic abundance ratios and a greater than terrestrial, although variable, abundance of C-13 relative to C-12.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- March 1976
- DOI:
- 10.1086/182072
- Bibcode:
- 1976ApJ...204L.135W
- Keywords:
-
- Abundance;
- Carbon Compounds;
- Interstellar Matter;
- Sulfides;
- Sulfur Isotopes;
- Data Reduction;
- Emission Spectra;
- Line Spectra;
- Molecular Rotation;
- Astrophysics