Abundance Analysis of Barium Stars

TL;DR

This study analyzes the chemical abundances of six barium stars and two CH subgiants, revealing overabundance of neutron capture elements likely due to wind accretion from AGB star companions, supporting binary evolution models.

Contribution

It provides detailed abundance measurements of barium and CH stars and confirms the wind accretion model as the explanation for their neutron capture element overabundance.

Findings

Neutron capture elements are overabundant in studied stars.

Abundance patterns are consistent with wind accretion from AGB stars.

Stars are part of the Galactic disk with near-solar metallicity.

Abstract

We obtain the chemical abundances of six barium stars and two CH subgiant stars based on the high signal-to-noise ratio and high resolution Echelle spectra. The neutron capture process elements Y, Zr, Ba, La, Eu show obvious overabundance relative to the Sun, for example, their [Ba/Fe] values are from 0.45 to 1.27. Other elements, including Na, Mg, Al, Si, Ca, Sc, Ti, V, Cr, Mn, Ni, show comparable abundances to the Solar ones, and their [Fe/H] cover a range from $-$0.40 to 0.21, which means they belong to Galactic disk. The predicts of the theoretical model of wind accretion for binary systems can explain the observed abundance patterns of the neutron capture process elements in these stars, which means that their overabundant heavy-elements could be caused by accreting the ejecta of AGB stars, the progenitors of the present white dwarf companions in the binary systems.