Probing the internal magnetism of stars using asymptotic magneto-asteroseismology

TL;DR

This paper develops a new method using asymptotic magneto-asteroseismology to probe the internal magnetic fields of stars by analyzing gravity and acoustic modes, enhancing understanding of stellar magnetism.

Contribution

It introduces a first-order perturbative approach to diagnose internal stellar magnetism through asymptotic mode analysis, expanding the tools available for stellar magnetic field studies.

Findings

Magnetic splittings of mode frequencies are explicitly derived.

Asymptotic modes can probe different magnetic field components.

Mixed-modes enhance the potential to study internal magnetism.

Abstract

Our knowledge of the dynamics of stars has undergone a revolution thanks to the simultaneous large amount of high-quality photometric observations collected by space-based asteroseismology and ground-based high-precision spectropolarimetry. They allowed us to probe the internal rotation of stars and their surface magnetism in the whole Hertzsprung-Russell diagram. However, new methods should still be developed to probe the deep magnetic fields in those stars. Our goal is to provide seismic diagnoses that allow us to sound the internal magnetism of stars. Here, we focus on asymptotic low-frequency gravity modes and high-frequency acoustic modes. Using a first-order perturbative theory, we derive magnetic splittings of their frequencies as explicit functions of stellar parameters. As in the case of rotation, we show how asymptotic gravity and acoustic modes can allow us to probe the different components of the magnetic field in the cavities where they propagate. This demonstrates again the high potential of using mixed-modes when this is possible.