Seismic signatures of stellar cores of solar-like pulsators: dependence on mass and age

TL;DR

This study investigates seismic diagnostic tools to infer stellar core properties and evolutionary states of solar-like pulsators by analyzing oscillation frequencies across different stellar masses and ages.

Contribution

It demonstrates the relation between seismic frequency slopes and core sound speed jumps, enabling inference of stellar age and core presence from oscillation data.

Findings

Frequency slopes correlate with core sound speed jumps.

Seismic tools can distinguish stars with and without convective cores.

The relation is independent of stellar mass.

Abstract

Useful information from the inner layers of stellar pulsators may be derived from the study of their oscillations. In this paper we analyse three diagnostic tools suggested in the literature built from the oscillation frequencies computed for a set of main sequence models with masses between $1.0\, {\rm M}_{\odot}$ and $1.6\, {\rm M}_{\odot}$, to check what information they may hold about stellar cores. For the models with convective cores ($M \geq 1.2\,{\rm M}_{\odot}$) we find a relation between the frequency slopes of the diagnostic tools and the size of the jump in the sound speed at the edge of the core. We show that this relation is independent of the mass of the models. In practice, since the size of the jump in the sound speed is related to the age of the star, using these seismic tools we may, in principle, infer the star's evolutionary state. We also show that when combining two of the three diagnostic tools studied, we are able to distinguish models with convective cores from models without a convective core but with strong sound-speed gradients in the inner layers.