Isotopic abundance variations in interstellar HCN

Journal Article · Sun May 15 04:00:00 EDT 1977 · Astrophys. J.; (United States)

DOI:https://doi.org/10.1086/155229· OSTI ID:7310695

Linke, R A; Goldsmith, P F; Wannier, P G; Wilson, R W; Penzias, A A

A study of the relative abundances of the rare isotopic species H/sup 12/C/sup 15/N and H/sup 13/C/sup 14/N has been made in six dense molecule clouds through observations of the 3.5 mm wavelength rotational transitions. The data indicate that in all sources the (HC/sup 15/N)/(H/sup 13/CN) integrated line-intensity ratio is smaller than that implied by terrestrial isotopic abundances. The excitation of HCN is discussed with special attention to the conditions which permit accurate abundance determination even when optical depths are large. We make a quantitative estimate of the line saturation and find this to be a small effect for the present measurements. There appears to be at least a factor of 6 between the average ratio for the sources in the galactic disk and that for two sources associated with the galactic center. This result is discussed in terms of increased nuclear processing in the galactic center region.

• Research Organization: Bell Laboratories, Holmdel, New Jersey
• OSTI ID: 7310695
• Journal Information: Astrophys. J.; (United States), Journal Name: Astrophys. J.; (United States) Vol. 214:1; ISSN ASJOA
• Country of Publication: United States
• Language: English

Related Subjects

640102* -- Astrophysics & Cosmology-- Stars & Quasi-Stellar
Radio & X-Ray Sources
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ABUNDANCE
CHEMICAL COMPOSITION
CHEMISTRY
COSMOCHEMISTRY
ELECTROMAGNETIC RADIATION
ENERGY-LEVEL TRANSITIONS
HYDROCYANIC ACID
HYDROGEN COMPOUNDS
HYPERFINE STRUCTURE
INORGANIC ACIDS
INTERSTELLAR SPACE
ISOTOPE RATIO
MOLECULES
RADIATIONS
RADIOWAVE RADIATION
SPACE
SPECTRA