Frequency distribution of /sup 12/C//sup 13/C ratios in G--K giants and carbon stars

Journal Article · Fri Jul 01 04:00:00 EDT 1977 · Astrophys. J.; (United States)

DOI:https://doi.org/10.1086/155347· OSTI ID:7304746

Scalo, J M

The low /sup 12/C//sup 13/C ratios found in G--K giants and supergiants, along with the fact that /sup 12/C//sup 13/C ratios in many carbon stars are larger than previously thought, suggest that the /sup 13/C in carbon stars is simply a leftover from the G--K giant phase of evolution. A preliminary test of this hypothesis is performed by transforming the frequency distribution of observed /sup 12/C//sup 13/C ratios in 49 G--K giants to a predicted distribution of /sup 12/C//sup 13/C in carbon stars using the distribution of observed C/O ratios in 61 carbon stars determined by Gow. The predicted distribution of /sup 12/C//sup 13/C ratios in carbon stars is then compared to the observed distribution for 22 carbon stars. Although the number of stars in the latter sample needs to be roughly tripled for a definitive test, the observed and predicted distrubutions differ sufficiently to conclude that the hypothesis is incorrect; at least some carbon stars have had /sup 13/C added to their atmospheres along with /sup 12/C, although the amount of additional /sup 13/C is not nearly so great as was previously thought. An alternate explanation involving mass transfer at the base of the giant branch is also possible.

• Research Organization: Department of Astronomy, University of Texas at Austin
• OSTI ID: 7304746
• Journal Information: Astrophys. J.; (United States), Journal Name: Astrophys. J.; (United States) Vol. 215:1; 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
CARBON 12
CARBON 13
CARBON ISOTOPES
CARBON STARS
CHEMICAL COMPOSITION
EVEN-EVEN NUCLEI
EVEN-ODD NUCLEI
GIANT STARS
ISOTOPE RATIO
ISOTOPES
LIGHT NUCLEI
NUCLEI
NUCLEOSYNTHESIS
STABLE ISOTOPES
STAR EVOLUTION
STARS
SUPERGIANT STARS