Austrian Early Career Conference 2024

Contribution:
Poster

Authors:
L. Einramhof [1] ; S.B. Das [1,2] ; L. Bugnet [1]

Affiliations:
1: Institute of Science and Technology Austria ; 2: Center for Astrophysics, Harvard & Smithsonian

Title:
Unveiling complex magnetic field configurations in red giant stars

Abstract:
Probing stellar internal magnetic fields is crucial in addressing the angular momentum transport problem in stars, which critically affects stellar evolution and age. Dipolar modes of stellar oscillation have very recently been used to make novel measurements of internal magnetic field strengths in red giant stars. This, however, relies on current state-of-the-art theory which can only infer the strength of the radial field component. Additionally, multiple magnetic field topologies may lead to the same signature in the dipolar oscillation frequencies, which we call topology degeneracy.
We show how a combined detection of magnetic signatures in dipolar and quadrupolar modes can significantly reduce the topology degeneracy. As a demonstration, we consider (a) purely dipolar, and (b) mixed dipolar and quadrupolar magnetic fields. We report how we can unambiguously infer essential topological parameters such as (i) the ratio between the dipolar and quadrupolar field strength and (ii) the inclination angles between the dipolar and quadrupolar fields with respect to the rotation axis.
Access to magnetic field topologies inside the core of red giants would result in a very strong impact on our understanding of angular momentum transport inside stars, and therefore on the current global picture of stellar evolution.