Abstract Details
| Name: Meenakshi P Affiliation: Christ (Deemed to be Univeristy) Conference ID: ASI2025_244 Title : Tracing accretion histories through high-resolution spectroscopy of extremely metal-poor stars: Insights from HE 0225−0546 and H Authors and Co-Authors : Meenakshi Purandardas, A V Sidharth, Blesson Mathew Abstract Type : Oral Abstract Category : Stars, Interstellar Medium, and Astrochemistry in Milky Way Abstract : The stellar halo of the Milky Way, though comprising only about 1% of the Galaxy’s stellar mass, serves as a critical time capsule, preserving the history of its formation and assembly. The halo contains millions of metal-poor stars, which are likely among the most ancient in the Galaxy and may even represent true second-generation stars. These stars carry the fossil records of the nucleosynthetic products from the very first stars, making them invaluable for understanding the early chemical evolution of the Milky Way. Over the past few decades, significant progress has been made through the study of metal-poor stars, revealing that more than half of the halo’s metal-poor stars likely originated from a single major accretion event, the Gaia–Sausage–Enceladus(GSE) dwarf galaxy. However, a comprehensive understanding of the Galaxy’s assembly history requires extending these studies beyond the solar neighborhood. In this study, we present high-resolution(R~60,000) spectroscopic analysis of two extremely metal-poor halo stars, HE0225−0546 and HE1153−0518, selected from the Hamburg ESO Survey using data obtained from the Subaru High Dispersion Spectrograph(HDS). We derived atmospheric parameters and chemical abundances, finding these stars to be extremely metal-poor with [Fe/H] ~-3.0. The stars are found to be relatively cooler with Teff~4850K and 4700K for HE0225−0546 and HE1153−0518 respectively. Both the stars are in the ascending phase of the red-giant branch. Although these stars are not in the evolutionary phase to produce heavy elements, they exhibit enhancement of these elements. Interestingly, the abundance patterns observed in these stars differ from those typical of Galactic halo metal-poor stars of similar metallicity, suggesting an external origin through accretion from other galaxies. In this talk, I will present some of the results obtained from the high-resolution spectroscopic analysis of HE0225−0546, and HE1153−0518 focusing on their accretion histories. |