A Catalog of 486 Barium Stars Identified in GALAH DR4

TL;DR

This paper presents the largest catalog of 486 Ba stars identified in GALAH DR4, analyzing their chemical, kinematic, and binary properties to understand their origins and nucleosynthesis processes.

Contribution

It introduces a new, extensive catalog of Ba stars with detailed chemical and kinematic analysis, including five newly identified Ba dwarfs and insights into their binary nature and nucleosynthesis origins.

Findings

Most Ba stars belong to the thin or thick disk.

Two stars show signatures of accreted populations.

[Ba/Fe] and [La/Fe] decline with increasing metallicity.

Abstract

We present a catalog of 486 Ba stars identified in the GALAH DR4 survey using high-resolution spectra and precise abundance measurements. The sample was selected based on s-process enrichment criteria involving the abundances of Ba and La relative to Eu, and further refined using the signed-distance method, resulting in the largest sample of Ba stars to date, including five newly identified Ba dwarfs. Using astrometric and kinematic parameters from Gaia DR3 and StarHorse, we derived the Galactic velocity components for 367 Ba stars and found that most belong to the thin or thick disk, while 18 exhibit halo-like kinematics. Chemical abundance analysis suggests that most Ba stars are of in situ origin, whereas two stars (4077588766331013248 and 6692980582560946304) display signatures of accreted populations. The E-Lz diagram further shows that star 4077588766331013248 lies within the region of substructure ED-8. The observed decline of [Ba/Fe] and [La/Fe] with increasing metallicity implies that s-process elements originate from nucleosynthetic sites distinct from those of iron-peak elements, while the decreasing [hs/ls] ratio toward higher metallicity indicates higher neutron capture efficiency at lower metallicity. Both giant and dwarf Ba stars-except for 6053735173729807872-are confirmed binaries hosting white dwarf companions. Moreover, we estimated the masses of the former asymptotic giant branch (AGB) companions to these Ba stars based on the good agreement between the FRUITY AGB model predictions and their observed abundance patterns.