Spectroscopic comparative study of the red giant binary system gamma Leonis A and B

Abstract

Gamma~Leo is a long-period visual binary system consisting of K0III (A) and G7III (B) giants, in which particular interest is attracted by the brighter A since the discovery of a planet around it. While detailed spectroscopic comparative study of both components would be worthwhile (e.g., for probing any impact of planet formation on chemical abundances), such a research seems to have been barely attempted as most available studies tend to be biased toward A. Given this situation, the physical properties of A and B along with their differences were investigated based on high-dispersion spectra in order to establish their stellar parameters, evolutionary status, and surface chemical compositions. The following results were obtained. (1) The masses were derived as ~1.7Msun and ~1.6Msun for A and B, respectively, both of which are likely to be in the stage of red clump giants after He-ignition. The mass of the planet around A has also been revised as m*sin(i) = 10.7M_Jupiter (increased by ~20%). (2) These are normal giants of subsolar metallicity ([Fe/H]~-0.4) belonging to the thin-disk population. (3) A as well as B show moderate C deficiency and N enrichment, which are in compatible with the prediction from the standard stellar evolution theory. (4) The chemical abundances of 26 elements are practically the same within <~0.1dex for both components, which implies that the surface chemistry is not appreciably affected by the existence of a planet in A.

17 pages including 8 tables and 8 figures (with electronic data as online material), accepted for publication in Astrophysics and Space Science

References in corpus (11)

• alpha-, r-, and s-process element trends in the Galactic thin and thick disks
• Basic physical parameters of a selected sample of evolved stars
• Medium-resolution Isaac Newton Telescope library of empirical spectra - II. The stellar atmospheric parameters
• Stellar parameters and chemical abundances of 223 evolved stars with and without planets
• Observable Signatures of Planet Accretion in Red Giant Stars I: Rapid Rotation and Light Element Replenishment
• Lithium in red giant stars: Constraining non-standard mixing with large surveys in the Gaia era
• Homogeneous spectroscopic parameters for bright planet host stars from the northern hemisphere
• Abundances of disk and Bulge giants from high-resolution optical spectra III. Sc, V, Cr, Mn, Co, Ni
• Detailed abundances of the wide pairs of stars with and without planets: the binary systems 16 Cyg and HD 219542
• Carbon 12C/13C isotope ratio of alpha Aurigae revised
• Mass evaluation for red giant stars based on the spectroscopically determined atmospheric parameters