CHEMICAL COMPOSITION OF THE COMPONENTS OF ECLIPSING BINARY STAR ZZ BOOTIS

• Published in: The Astronomical journal 2012-08, Vol.144 (2), p.1-11, Article 35
• Main Authors: Kang, Young-Woon, Yushchenko, Alexander, Hong, Kyengsoo, Kim, Sungeun, Yushchenko, Volodymyr
• Format: Article
• Language: English
• Subjects: Abundance; ACCRETION DISKS; ASTRONOMY; ASTROPHYSICS; ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; Atmospheres; Atmospherics; BARIUM; BINARY STARS; CHEMICAL COMPOSITION; COMPARATIVE EVALUATIONS; Eclipsing binary stars; ELEMENT ABUNDANCE; EMISSION SPECTRA; Errors; GRAVITATION; IONIZATION POTENTIAL; IRON; Metallicity; OXYGEN; RARE EARTHS; ROTATION; STELLAR ATMOSPHERES; TELESCOPES; VISIBLE RADIATION
• ISSN: 1538-3881; 0004-6256; 1538-3881
• DOI: 10.1088/0004-6256/144/2/35

We investigated ZZ Boo using a high-resolution (R = 80,000) spectrum obtained at the BOES echelle spectrograph attached to a 1.8 m telescope at the Bohuynsan observatory in Korea. The atmospheric parameters of the components were found using the published photometrical observations and the abundance analysis of iron lines: the flux ratio of the components F sub(A)/F sub(B) = 1.12 + or - 0.15, the effective temperatures of the components T sub(eff) = 6860 + or - 20 K and 6930 + or - 20 K, the surface gravities log g = 3.72 + or - 0.10 and 3.84 + or - 0.10, the metallicities [Fe/H] = -0.10 + or - 0.08 and -0.03 + or - 0.10, and the projected rotation velocities v sin i = 11.9 + or - 0.4 km s super(-1) and 19.3 + or - 0.8 km s super(-1) for the primary and secondary components, respectively. The pointed errors are the formal errors of the methods used; the systematic errors of the temperatures, gravities, metallicities, and projected rotational velocities can be as high as 250-300 K, 0.3 dex, 0.15 dex, and 4 km s super(-1), respectively. The abundances of 24 and 22 chemical elements were determined in the atmospheres of the components. The abundance pattern of the primary component shows the solar or slightly undersolar abundances of all elements. CNO abundances are close to solar values. The abundance pattern of this component resembles those of [lambda] Boo type stars. The abundances of light elements, except oxygen, in the atmosphere of the secondary component are practically solar. The abundances of barium and two detected lanthanides are close to the solar values; the overabundance of oxygen is 0.9 dex. The abundances of two components are evidently different. The comparison of relative abundances with the condensation temperatures and second ionization potentials of the elements confirms the difference in abundance patterns and allows discussion of the different accretion scenarios for two components of this binary system.