On the Occurrence of Enhanced Lithium in Magellanic Cloud Red Giants
Abstract
High-resolution spectra have been obtained for 27 red giants in the Magellanic Clouds spanning a range in bolometric absolute magnitudes (M_bol_ ~ -5 to -9). In a previous study, we found that five out of five luminous asymptotic giant branch (AGB) stars in the Small Magellanic Cloud (SMC) showed enhanced Li I resonance doublets (6707 A); the extension here of our previous work reveals that the "Li- strong" red giants in both Magellanic Clouds are luminous (M_bol_ ~ -6 to -7) stars on the AGB. Lower luminosity (M_bol_ ~ -5.0 to -5.5) AGB stars show no Li I features, while the very luminous (M_bol_ ~ -7 to -9) red giants that are identified as massive, core-burning supergiants also show no Li I features. We suggest that the enhanced Li abundances in these luminous AGB stars are a byproduct of envelope burning in the more massive (M ~ 4-8 M_sun_) AGB stars. We also demonstrate that these Li-strong AGB stars may be a significant source of ^7^Li in a galaxy.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- October 1990
- DOI:
- 10.1086/185829
- Bibcode:
- 1990ApJ...361L..69S
- Keywords:
-
- Abundance;
- Asymptotic Giant Branch Stars;
- Lithium;
- Magellanic Clouds;
- Red Giant Stars;
- Metallicity;
- Nuclear Fusion;
- Spectral Resolution;
- Stellar Evolution;
- Stellar Luminosity;
- Astrophysics;
- STARS: ABUNDANCES;
- STARS: EVOLUTION