C-12/C-13 isotope ratio across the Galaxy from observations of C-13/O-18 in molecular clouds

view Abstract Citations (354) References (45) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS 12C/ 13C Isotope Ratio across the Galaxy from Observations of 13C 18O in Molecular Clouds Langer, William D. ; Penzias, Arno A. Abstract The carbon isotopic ratio across the Galaxy was studied by observing nine interstellar clouds in the doubly rare isotope of carbon monoxide, C-13/O-18, and in the rare isotopic species C-12/O-18. The goal in this study was to improve the data from optically thin carbon monoxide emissions. A systematic gradient is found in the C-12/C-13 isotopic ratio across the Galaxy, ranging from about 30 in the inner part at 5 kpc to about 70 at 12 kpc, with a Galactic center value of 24. Near the solar radius the average ratio is 57, but it is somewhat larger, about 67, in Orion. Carbon monoxide isotopic ratios are smaller than those of formaldehyde, but they have roughly the same slope across the Galaxy. The result of 57 for the local CO ratio lies between the values from various CH(+) absorption measurements. Publication: The Astrophysical Journal Pub Date: July 1990 DOI: 10.1086/168935 Bibcode: 1990ApJ...357..477L Keywords: Carbon Monoxide; Carbon 13; Interstellar Gas; Milky Way Galaxy; Molecular Clouds; Oxygen 18; Chemical Evolution; Nuclear Astrophysics; Star Formation Rate; Stellar Evolution; Astrophysics; GALAXIES: THE GALAXY; INTERSTELLAR: ABUNDANCES; INTERSTELLAR: MOLECULES full text sources ADS | data products SIMBAD (11)