The Isotopic Composition of Cosmic-Ray B, C, N, and O: Evidence for an Overabundance of 18O
Abstract
New observations of galactic cosmic rays at higher energies (about 400-780 MeV/nucleon) than obtained in previous direct mass measurements have resulted in determinations of the isotopic composition of B, C, N, and O. The derived cosmic-ray source abundances provide evidence for an enhancement of O-18/O-16 by a factor of 5.6 +/- 1.9 over the solar system value and give a C-13/C-12 ratio consistent with the solar system abundance ratio, but lower than some recent measurements of the local interstellar medium.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- June 1992
- DOI:
- 10.1086/186405
- Bibcode:
- 1992ApJ...391L..89G
- Keywords:
-
- Chemical Composition;
- Cosmochemistry;
- Galactic Cosmic Rays;
- Galactic Evolution;
- Nitrogen Isotopes;
- Oxygen Isotopes;
- Boron Isotopes;
- Carbon Isotopes;
- Interstellar Chemistry;
- Solar System;
- Space Radiation;
- GALAXY: ABUNDANCES;
- ISM: COSMIC RAYS