Asteroseismic Signatures of Small Convective Cores

TL;DR

This paper analytically investigates how small convective cores influence the oscillation frequencies of solar-like stars, proposing a diagnostic method to detect core signatures using a combination of observed frequencies.

Contribution

It introduces an analytical approach to identify convective core signatures in stellar oscillations and validates a diagnostic tool with simulated data for application to satellite observations.

Findings

Derived an expression for frequency perturbations caused by small convective cores.

Proposed a diagnostic tool to isolate core signatures from oscillation data.

Validated the tool with simulated data, applicable to CoRoT and Kepler observations.

Abstract

We present an analytical study of the effect of small convective cores on the oscillations of solar-like pulsators. Based on an asymptotic analysis of the wave equation near the center of the star, we derive an expression for the perturbations to the frequencies of radial modes generated by a convective core and discuss how these perturbations depend on the properties of the core. Moreover, we propose a diagnostic tool to isolate the predicted signature of the core, constructed from a particular combination of the oscillation frequencies, and we validate this tool with simulated data. We also show that the proposed tool can be applied to the pulsation data soon expected from satellite missions such as CoRoT and Kepler to constrain the amplitude of the discontinuity in the sound speed at the edge of the convective core, the ratio between the sound speed and the radius at this same location, and the stellar age.