The non-local thermodynamic equilibrium barium abundance in dwarf stars in the metallicity range of inline image

Authors

  • S. Korotin,

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    1. Astronomical Observatory of Odessa National University, and Isaac Newton Institute of Chile Odessa branch, 65014 Odessa, Ukraine
      E-mail: serkor@skyline.od.ua
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  • T. Mishenina,

    1. Astronomical Observatory of Odessa National University, and Isaac Newton Institute of Chile Odessa branch, 65014 Odessa, Ukraine
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  • T. Gorbaneva,

    1. Astronomical Observatory of Odessa National University, and Isaac Newton Institute of Chile Odessa branch, 65014 Odessa, Ukraine
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  • C. Soubiran

    1. Université Bordeaux 1, CNRS – Laboratoire d’Astrophysique de Bordeaux, UMR 5804, 33370 Floirac, France
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E-mail: serkor@skyline.od.ua

ABSTRACT

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.

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