Gravity modes and mixed modes as probes of stellar cores in main-sequence stars: from solar-like to beta Cep stars

TL;DR

This paper explores how gravity and mixed mode frequencies in main-sequence stars reveal details about the core's chemical composition gradient and the effects of transport processes like turbulent mixing.

Contribution

It introduces a simple analytical description linking gravity mode period spacings to the core's e gradient and examines the impact of mixing processes on mode periods.

Findings

High-order gravity modes follow a uniform period spacing with an oscillatory component.

The periodicity and amplitude of the oscillations relate to the e gradient's location and sharpness.

Turbulent mixing affects both high-order and low-order g modes, as well as mixed modes.

Abstract

We investigate how the frequencies of gravity modes depend on the detailed properties of the chemical composition gradient that develops near the core of main-sequence stars and, therefore, on the transport processes that are able to modify the \mu profile in the central regions. We show that in main-sequence models, similarly to the case of white dwarfs, the periods of high-order gravity modes are accurately described by a uniform period spacing superposed to an oscillatory component. The periodicity and amplitude of such component are related, respectively, to the location and sharpness of the \mu gradient. We briefly discuss and interpret, by means of this simple approximation, the effect of turbulent mixing near the core on the periods of both high-order and low-order g modes, as well as of modes of mixed pressure-gravity character.