Asteroseismic Structure Inversions of Main-Sequence Solar-like Oscillators with Convective Cores

TL;DR

This study applies asteroseismic structure inversions to 43 main-sequence stars with convective cores observed by Kepler, assessing the accuracy of stellar models and exploring physical processes to resolve discrepancies.

Contribution

It extends previous inversion analyses to stars with convective cores and evaluates the impact of various physical processes on model accuracy.

Findings

About half of the stars' structures are well-reproduced by models within uncertainties.

Inversions reveal cases of both overestimated and underestimated sound speeds in models.

Physical modifications tested did not significantly resolve the identified structural differences.

Abstract

Asteroseismic inferences of main-sequence solar-like oscillators often rely on best-fit models. However, these models cannot fully reproduce the observed mode frequencies, suggesting that the internal structure of the model does not fully match that of the star. Asteroseismic structure inversions provide a way to test the interior of our stellar models. Recently, structure inversion techniques were used to study 12 stars with radiative cores. In this work, we extend that analysis to 43 main-sequence stars with convective cores observed by Kepler to look for differences in the sound speed profiles in the inner 30% of the star by radius. For around half of our stars, the structure inversions show that our models reproduce the internal structure of the star, where the inversions are sensitive, within the observational uncertainties. For the stars where our inversions reveal significant differences, we find cases where our model sound speed is too high and cases where our model sound speed is too low. We use the star with the most significant differences to explore several changes to the physics of our model in an attempt to resolve the inferred differences. These changes include using a different overshoot prescription and including the effects of diffusion, gravitational settling, and radiative levitation. We find that the resulting changes to the model structure are too small to resolve the differences shown in our inversions.