| Name: Anjali Singh |
| Affiliation: Indian Institute of Technology(BHU), Varanasi |
| Conference ID: ASI2026_362 |
| Title: Asteroseismic inference of helium abundance in a sample of 77 cool stars |
| Abstract Type: Poster |
| Abstract Category: Stars, Interstellar Medium, and Astrochemistry in Milky Way |
| Author(s) and Co-Author(s) with Affiliation: Anjali Singh(Indian Institute of Technology(BHU), Varanasi, Varanasi - 221005, India), Kuldeep Verma(Indian Institute of Technology(BHU), Varanasi, Varanasi - 221005, India) |
| Abstract: The internal structure of stars is influenced by their chemical composition. The surface abundances of metals can be reliably measured by spectroscopic observations, but the direct measurement of helium is not possible because the envelope temperature of such stars is inadequate to excite helium. Fortunately, the observed oscillation frequencies of solar-like oscillators are influenced by the helium ionization zone, and hence they can be used to estimate the surface helium abundance. We derive the seismic signal of the helium ionization zone for a sample of 77 solar-like oscillators using high-quality data from multiple sources, including the Kepler LEGACY sample, the KAGES sample, and a few K2 stars. We estimated helium ionization zone parameters of these stars using helium signatures. We computed a dense stellar model grid with up-to-date input physics containing about 30,000 tracks spanning a large parameter space and approximately 19 million models. We fitted observed helium ionization zone parameters along with frequency ratios and spectroscopic observables to the predictions of stellar models in a Bayesian framework and estimated physical parameters such as mass, radius, age, and initial helium and metal mass fractions for all 77 stars in our sample. We use the inferences of initial helium and metal mass fractions, along with age, to study helium enrichment in the Milky Way. In this presentation, I shall discuss the findings of our study. |
