Journal Article

The non-local thermodynamic equilibrium barium abundance in dwarf stars in the metallicity range of −1 < [Fe/H] < +0.3

S. Korotin, T. Mishenina, T. Gorbaneva and C. Soubiran

in Monthly Notices of the Royal Astronomical Society

Published on behalf of The Royal Astronomical Society

Volume 415, issue 3, pages 2093-2100
Published in print August 2011 | ISSN: 0035-8711
Published online August 2011 | e-ISSN: 1365-2966 | DOI: http://dx.doi.org/10.1111/j.1365-2966.2011.18805.x
The non-local thermodynamic equilibrium barium abundance in dwarf stars in the metallicity range of −1 < [Fe/H] < +0.3

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We present the results of determination of the barium abundance considering the non-local thermodynamic equilibrium (NLTE) effects in 172 dwarf stars in the metallicity range of −1 < [Fe/H] < +0.3, assigned to different Galactic substructures by kinematic criteria. We used a model of the Ba atom with 31 levels of Ba i and 101 levels of Ba ii. The atmosphere models for the investigated stars were computed using the atlas9 code modified by new opacity distribution functions by Castelli & Kurucz. The NLTE profiles of the unblended Ba ii (4554, 5853, 6496 Å) were computed and then compared to those observed. The line 6141 Å was also used, but with an allowance for its correlation with the iron line. The average barium abundances in the thin and thick discs are 0.01 ± 0.08 and −0.03 ± 0.07, respectively. The comparison to the calculations of the Galactic chemical evolution by Serminato et al. was conducted. The trend obtained for the Ba abundance versus [Fe/H] suggests a complex barium production process in the thin and thick discs.

Keywords: stars: abundances; stars: late-type; Galaxy: disc; Galaxy: evolution

Journal Article.  4589 words.  Illustrated.

Subjects: Astronomy and Astrophysics

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