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Abstract Barium (Ba) stars belong to binary systems that underwent mass-transfer events. As a consequence, their envelopes were enriched with material synthesized in the interiors of their evolved companions via slow neutron-capture nucleosynthesis, the s -process. As postinteracting binaries, Ba stars figure as powerful tracers of the s -process. In this study, we conduct a classical local thermodynamic equilibrium analysis for a sample of 180 Ba giant stars to find complementary insights for the s -process, in form of elemental abundances of carbon, nitrogen, and oxygen, as well as the 12 C/ 13 C ratio. We found carbon abundances systematically larger than those observed in normal giants, with C/Fe ratios ranging within from −0.30 to +0.60 dex. As expected, the C/Fe ratios increase for lower metallicity regimes and are strongly correlated with the average s -process abundances. Nitrogen abundances have a flat behavior around N/Fe ∼ +0.50 dex and are moderately correlated with sodium abundances. Except for HD 107541, the entire sample shows C/O 60 for three objects.
Roriz et al. (Thu,) studied this question.