The NLTE Barium Abundance in Dwarf Stars in the Metallicity Range of -1 < [Fe/H] < +0.3

TL;DR

This study investigates the non-LTE barium abundances in 172 dwarf stars across different Galactic substructures, revealing complex production processes and comparing results with Galactic chemical evolution models.

Contribution

It provides the first detailed NLTE barium abundance analysis for a large sample of dwarf stars in the specified metallicity range, incorporating advanced atomic models and atmosphere computations.

Findings

Average Ba abundance in thin disc: 0.01 +/- 0.08

Average Ba abundance in thick disc: -0.03 +/- 0.07

Complex barium production processes inferred from abundance trends

Abstract

We present the results of determination of the barium abundance considering the non-LTE (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. The NLTE profiles of the unblended Ba II (4554 A, 5853 A, 6496 A) were computed and then compared to those observed. The line 6141 A 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. (2009) was conducted. The trend obtained for the Ba abundance versus [Fe/H] suggests a complex barium production process in the thin and thick discs.