Deneb's Light-Element Abundances Revisited
Abstract
A revised non-LTE analysis of Deneb (A2 Ia supergiant), based on our new observational data, was performed in order to reinvestigate its photospheric abundances of He, C, N, O, Na, and S by using the model atmosphere (T_eff = 9000 K, log g = 1.5), which satisfies the ionization equilibria of C/S and has a T_eff lower by 1000 K than that adopted in the previous work of Takeda (1994; AAA 61.114.112). Owing to this model change, the abundance of He has turned out to be nearly normal on the average, in contrast to the conclusion in that old study, which suggested a considerable deficiency. However, the abundances from individual HeI lines show a rather large diversity with an apparent wavelength-dependence, which remains to be explained. Regarding the abundances of C, N, O, Na, and S relative to the Sun, C is conspicuously underabundant by ~ 0.8 dex, N, Na, and S show a moderate excess of 0.3--0.4 dex, and O seems to be mildly deficient by ~ 0.3 dex; this abundance pattern appears to conform to the common tendency seen with other supergiants in this temperature range.
- Publication:
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Publications of the Astronomical Society of Japan
- Pub Date:
- October 1996
- DOI:
- 10.1093/pasj/48.5.753
- Bibcode:
- 1996PASJ...48..753T
- Keywords:
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- STARS: ABUNDANCES;
- STARS: ATMOSPHERES;
- STARS: EARLY-TYPE;
- STARS: INDIVIDUAL (DENEB);
- STARS: SUPERGIANTS