Abstract Details
| Name: Lupamudra Sarmah Affiliation: Indian Institute of Astrophysics Conference ID: ASI2025_631 Title : Asteroseismic insights into Barium stars: Probing companion information and formation pathways Authors and Co-Authors : Lupamudra Sarmah 1, Bharat Kumar Yerra 1 Abstract Type : Oral Abstract Category : Stars, Interstellar Medium, and Astrochemistry in Milky Way Abstract : Barium (Ba) stars are a group of G-K-type stars found across dwarf and giant phases that exhibit unusually enhanced abundances of slow (s) neutron-capture elements. This enhancement is often attributed to binary mass transfer from an asymptotic giant branch (AGB) companion, which has now become a CO white dwarf (WD). However, the accretion and mass transfer in these systems remains poorly understood. In this study, we have performed a detailed asteroseismic analysis of a sample of 20 Ba dwarf and giant systems with known orbital parameters in the TESS (Transiting Exoplanet Survey Satellite) field. We derived precise seismic masses of the primary Ba stars and then estimated companion WD mass and their progenitor AGB masses. Our results show that Ba stars have two populations of AGB companions, with the majority having low-mass AGB companions but showing a wide range of [s/Fe]. This suggests that dilution after mass transfer may play an important role. Interestingly, the masses of the WDs also revealed 3 peculiar Ba stars (2 giants and 1 dwarf) with Helium (He) WD companions (<0.5M⨀). This finding contradicts the standard mass-transfer hypothesis, as the progenitors of He WDs do not go through the AGB phase. In this talk, I will present these findings and discuss the possible alternative formation pathways for these peculiar cases of Ba stars. |