1980/08/01 by A. Wootten, E. P. Bozyan, D. B. Garrett +2 · 2 citations
Physics and Astronomy · Earth and Planetary Sciences · Chemistry · #Astrophysics and Star Formation Studies #Atmospheric Ozone and Climate #Molecular Spectroscopy and Structure
paper · doi:10.1086/158168
openalex publication_date 1980/08/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/06/11
We have surveyed a wide variety of interstellar clouds for the radical C<SUB>2</SUB>H including a number of cold dust clouds in which star formation is not known to be occurring (yet). We have also examined small dust clouds with single infrared sources or Herbig-Haro objects. Definite detections of C<SUB>2</SUB>H were made in 19 of the 30 regions examined with a further 3 possible detections. C<SUB>2</SUB>H was detected in 8 cold dust clouds. We have made extensive maps of the unusual dust cloud L1534 (TMC 1) and of the M17SW star-formation region. Smaller maps of B227, L43, and L134N were also made. The L1534 and M17SW maps show that the C<SUB>2</SUB>H distribution is well correlated with that of other molecular species in these clouds. The fractional abundance of C<SUB>2</SUB>H in cold clouds is typically found to be X(C<SUB>2</SUB>H) ≈ 6 × 10<SUP>-9</SUP>. The molecule HC<SUB>3</SUB>N is thought to have the same chemical precursor, C<SUB>2</SUB>H<SUB>2</SUB><SUP>+</SUP>, as the C<SUB>2</SUB>H molecule. The ratio of abundances X(C<SUB>2</SUB>H)/X(HC<SUB>3</SUB>N) tests the chemical formation path, and it falls in the range of 3-10, consistent with the ratio expected from gas phase molecule formation models. There is no evidence, however, for a greater abundance decrease of X(C<SUB>2</SUB>H) with increasing density than for other molecular species in any of the clouds we have examined.