The chemical composition of late-type supergiants. II. Lithium abundances for 19 G and K Ib stars.
Abstract
From an analysis of high-resolution, high-signal-to-noise spectra, lithium abundances or upper limits are derived for 19 0 and K Ib stars. The abundances range over a factor of 50 with a maximum logarithmic abundance determined of +1.5 [relative to log E(H) = 12]. Non-LTE effects are found to be significant, particularly in later-type stars. The mean internal error of an individual abundance is approximately 0.2 dex. The relation between lithium and 12C/13C is explored and the functional form is found to be best interpreted as a step function. Various mechanisms for lowering 12C!13C ratios are constrained by the derived lithium abundances. Meridional mixing is found to be the most viable mechanism for lowering 12C/13C ratios in Ib stars. Subject headings: stars: abundances - stars: late-type - stars: supergiants
- Publication:
-
The Astrophysical Journal
- Pub Date:
- December 1977
- DOI:
- 10.1086/155731
- Bibcode:
- 1977ApJ...218..752L
- Keywords:
-
- Abundance;
- Chemical Composition;
- G Stars;
- K Stars;
- Late Stars;
- Lithium;
- Stellar Spectrophotometry;
- Supergiant Stars;
- Atmospheric Turbulence;
- Carbon 12;
- Carbon 13;
- Convective Flow;
- Spectral Resolution;
- Spectrum Analysis;
- Stellar Evolution;
- Stellar Mass Ejection;
- Stellar Models;
- Stellar Temperature;
- Astrophysics