The Chemical Compositions of the SRD Variable Stars. III. KK Aquilae, AG Aurigae, Z Aurigae, W Leo Minoris, and WW Tauri
Abstract
Chemical compositions are derived from high-resolution spectra for five field SRd variables. These supergiants not previously analyzed are shown to be metal poor: KK Aql with [Fe/H]=-1.2, AG Aur with [Fe/H]=-1.8, Z Aur with [Fe/H]=-1.4, W LMi with [Fe/H]=-1.1, and WW Tau with [Fe/H]=-1.1. Their compositions are, except for two anomalies, identical to within the measurement errors to the compositions of subdwarfs, subgiants, and less evolved giants of the same [Fe/H]. One anomaly is an s-process enrichment for KK Aql, the first such enrichment reported for an SRd variable. The second and more remarkable anomaly is a strong lithium enrichment for W LMi, also a first for field SRd variables. The Li I λ6707 profile is not simply that of a photospheric line but includes strong absorption from redshifted gas, suggesting, perhaps, that lithium enrichment results from accretion of Li-rich gas. This potential clue to lithium enrichment is discussed in light of various proposals for lithium synthesis in evolved stars.
- Publication:
-
Publications of the Astronomical Society of the Pacific
- Pub Date:
- December 2000
- DOI:
- 10.1086/317721
- arXiv:
- arXiv:astro-ph/0008428
- Bibcode:
- 2000PASP..112.1559G
- Keywords:
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- Stars: Abundances;
- Stars: Variables: Other;
- Stars: AGB and Post-AGB;
- Astrophysics
- E-Print:
- 18 pages of text, 8 tables, 2 figures. Accepted for publication in PASP