Elemental abundances of the supergiant stars σ Cygnus and η Leonis
Abstract
This study aims to analyse the elemental abundances for the late B type supergiant star σ Cyg and the early A-type supergiant η Leo using ATLAS9 (Kurucz, 1995; Sbordone et al., 2004), assuming local thermodynamic equilibrium (LTE). The spectra used in this study are obtained from Dominion Astrophysical Observatory and have high resolution and signal-to-noise ratios. The effective temperature and the surface gravity of σ Cyg are determined from the ionisation equilibria of Al I/II, Mg I/II, Fe I/II, Fe II/III, and by fitting to the wings of Hγ and Hβ profiles as Teff = 10388 K and log g = 1.80. The elemental abundances of η Leo are determined using Teff = 9600 K and log g = 2.00, as reported by Przybilla et al. (2006). The ionisation equilibria of C I/II, N I/II, Mg I/II, Ca I/II, Cr I/II and Fe I/II/III are also satisfied in the atmosphere of η Leo. The radial velocities of σ Cyg and η Leo are -7.25 ± 7.57 km s-1 and 10.40 ± 13.37 km s-1, respectively. The derived projected rotational velocities vsini from synthetic spectra are 27 and 2 km s-1 for both stars, respectively. The macroturbulent velocities (ζ) are 24 ± 2 km s-1 and 14.5 ± 1.5 km s-1. Also, the microturbulent velocities (ξ) have been determined for both of stars as 3.5 km s-1. The CNO abundance results of σ Cyg and η Leo show C deficiency, N overabundance and O in excess.
- Publication:
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New Astronomy
- Pub Date:
- December 2013
- DOI:
- 10.1016/j.newast.2013.03.013
- arXiv:
- arXiv:1512.04557
- Bibcode:
- 2013NewA...25...50T
- Keywords:
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- Astrophysics - Solar and Stellar Astrophysics
- E-Print:
- 8 tables, 6 figures, and 45 pages, Published in New Astronomy