Oxygen Isotopic Abundances in Evolved Stars. III. 26 Carbon Stars
Abstract
Oxygen isotope ratios have been measured in 21 ordinary N-type carbon stars and in five 13C-rich J-type stars. The ratios in the ordinary N-type stars are 550 ≤ 16O/17O ≤ 4100 and 700 ≤ 16O/18O ≤ 2400. These ratios are much higher than expected and are extremely difficult to explain in terms of present theories of stellar evolution. The J-type stars exhibit ratios 350 ≤ 16O/17O ≤ 850, 16O/18O ratios being very uncertain. Together with nitrogen abundances measured by Lambert et al., these ratios preclude the envelope burning (hot-bottom convection) hypothesis which has been proposed for these stars.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- May 1987
- DOI:
- 10.1086/165201
- Bibcode:
- 1987ApJ...316..294H
- Keywords:
-
- Carbon Stars;
- Oxygen Isotopes;
- Stellar Composition;
- Stellar Evolution;
- Astronomical Catalogs;
- Oxygen 17;
- Oxygen 18;
- Stellar Envelopes;
- Astrophysics;
- STARS: ABUNDANCES;
- STARS: CARBON;
- STARS: EVOLUTION