Two barium stars in the Galactic bulge

TL;DR

This study reports the discovery of the first two barium stars in the Galactic bulge, analyzing their elemental abundances to test nucleosynthesis models and estimating their frequency in this environment.

Contribution

It is the first identification and detailed abundance analysis of barium stars in the Galactic bulge, providing new insights into stellar evolution and chemical enrichment.

Findings

Confirmed two stars as barium stars with high barium excesses

Estimated a 1% frequency of barium stars in the Galactic bulge

Compared elemental abundances with nucleosynthesis models

Abstract

Barium stars conserve important information on the s-process and the third dredge-up in intermediate mass stars. Their discovery in various environments is therefore of great help to test nucleosynthesis and mixing models. Our aim is to analyse two stars with a very strong barium line detected in a large survey of red giants in the Galactic bulge. Abundance analysis was done comparing synthetic model spectra based on the COMARCS code with our medium resolution spectra. Abundances of Ba, La, Y, and Fe were determined. Beside the two main targets, the analysis was also applied to two comparison stars. We confirm that both stars are barium stars. They are the first ones of this kind identified in the Galactic bulge. Their barium excesses are among the largest values found up to now. The elemental abundances are compared with current nucleosynthesis and mixing models. Furthermore, we estimate a frequency of barium stars in the Galactic bulge of about 1%, which is identical to the value for disc stars.