Diagnostics from solar and stellar glitches

TL;DR

This paper reviews how stellar oscillation signatures caused by internal structural changes can reveal physical processes like diffusion, chemical mixing, and composition, leveraging space-based data across different star types.

Contribution

It synthesizes theoretical and observational advances in analyzing stellar glitches to infer internal stellar processes across various star types.

Findings

Identification of signatures linked to internal structural features.

Extension of solar and white dwarf analysis methods to diverse stars.

Potential to determine helium content and mixing processes in stars.

Abstract

Sudden changes in the internal structure of stars, placed at the interface between convective and radiative regions, regions of partial ionisation, or between layers that have acquired different chemical composition as a result of nuclear burning, often produce specific signatures in the stars oscillation spectra. Through the study of these signatures one may gain information on the physical processes that shape the regions that produce them, including diffusion and chemical mixing beyond the convectively unstable regions, as well as information about the helium content of stars. In this talk, I will review important theoretical and observational efforts conducted over the years towards this goal. I will emphasise the potential offered by the study of acoustic, gravity, and mixed modes observed in stars of different mass and evolutionary stages, at a time when space-based data is allowing us to build on the knowledge gained from the study of the sun and white dwarfs, where these efforts have long been undertaken, extending the methods developed to stars across the HR diagramme.