Detailed Asteroseismic Modeling of 8 α-element Enhanced Metal Poor Stars

Combining asteroseismic and spectroscopic observations with stellar modeling offers a powerful method for precisely determining the fundamental properties of stars in different kinematic components of our galaxy. In this work, we analyze individual oscillation mode frequencies of eight metal-poor, α-enhanced stars. In addition to determining their fundamental properties like age, we model these stars using both a full treatment of α-enhancement and an ad hoc correction to total metallicity, showing that properly accounting for α-enhanced abundances and opacities generally reduces the inferred asteroseismic ages. Comparing results from individual mode modeling with those based on asteroseismic scaling relations, we find that masses derived from global asteroseismic parameters are significantly overestimated relative to our detailed modeling. This discrepancy is most pronounced at low metallicities and may indicate a breakdown of the νmax scaling relation for metal-poor stars, consistent with recent findings. Understanding the extent to which the νmax scaling relation fails for low-metallicity solar-like oscillators through detailed modeling will enable more accurate mass and age determinations for hundreds of giant stars in the Galactic stellar halo for which only global asteroseismic parameters are available.