A fine analysis of calcium and iron lines in the spectrum of the K0 giantPollux: accurate fundamental parameters.
Abstract
This paper describes a model atmosphere analysis of calcium and iron lines in the spectrum of the bright K0 giant Pollux. The assumption of LTE is initially retained throughout a coarse analysis in which the proprieties of various model atmospheres are examined and approximate values for the atmospheric parameters are derived. A fine analysis follows in which an empirical model atmosphere, based on the observed profile of the Ca II 8542 A line, is constructed. The parameter results obtained include T(e) = 4865 + or - 50 K, surface gravity log g = 2.75 + or - 0.15 dex, logarithmic iron abundance relative to the sun (Fe/H) = -0.0-4 + or - 0.05 dex, logarithmic calcium abundance (relative to H = 12.00) = Ca/H = 6.25 + or - 0.1 dex, and the microturbulence is 1.4 + or - 0.1 km/s. Weak, high-excitation Fe I lines appear to be formed in conditions close to LTE. The spectroscopic mass of Pollux is derived to be 1.7 solar.
- Publication:
-
Monthly Notices of the Royal Astronomical Society
- Pub Date:
- May 1991
- DOI:
- 10.1093/mnras/250.1.89
- Bibcode:
- 1991MNRAS.250...89D
- Keywords:
-
- Calcium;
- Fine Structure;
- Giant Stars;
- Iron;
- K Stars;
- Line Spectra;
- Stellar Spectra;
- Stellar Atmospheres;
- Stellar Composition;
- Stellar Models;
- Visible Spectrum;
- Astrophysics