Hidden magnetic fields in stellar interiorsprobed by asteroseismology

Understanding the role of internal magnetic fields in stars remains a
major stumbling block for the description of angular momentum transport and
stellar evolution. In this work, we present a new implementation of the 2D
oscillation code ACOR, which incorporates the effects of both stellar rotation
and magnetic fields. The code has been rendered modular, allowing to specify
the set of equations to solve and the hypotheses through a symbolic calculus
approach. The full set of adiabatic, non-radial pulsation equations is solved
using a spectral approach in the angular direction and high-order finite
differences in the radial direction. As a first step, we focus on a simplified case
in which the magnetic field is purely toroidal, axisymmetric, and aligned with
the star’s rotation axis. The numerical results are validated against first-order
perturbative predictions in the weak-field regime. We show that internal
magnetic fields leave distinct signatures in the period spacing of g-modes.
These features provide a promising seismic diagnostic to probe deep stellar
magnetism. Future work will aim to extend this framework to more realistic
magnetic field topologies and a broader range of pulsating stars, including red
giants.