Work

Combining the effects of mixed modes and magnetic instabilities in angular momentum transport

Year: 2025

Type: article

Abstract: Core rotation rates of red-giant stars inferred‬‭ from asteroseismic‬ ‭observations are substantially lower than predicted by current stellar models.‬‭This indicates the lack of an efficient angular momentum (AM) transport‬ mechanism within radiative interiors. Mixed modes are a promising candidate‬ to extract AM from the core of evolved red giants. However, in our previous‬ work (Bordadágua et al., 2025), we found that an additional physical‬ mechanism is required to redistribute the localised spin-down due to the mixed‬ modes and to explain the observations. Using a post-processing code to‬ compute the AM transport in stellar models, we investigate the interaction‬ between the mixed mode mechanism and the well known‬ magneto-hydrodynamic (MHD) instability revised by Fuller et al. (2019). The‬ incorporation of this MHD instability can potentially enhance the AM transport‬ efficiency of mixed modes. We compare the final rotation rates of our models‬‭with asteroseismic observations, and discuss possible constraints on the free‬ parameters of both AM transport mechanisms.‬

Source: Zenodo (CERN European Organization for Nuclear Research)

DOI: 10.5281/zenodo.17054187

Authors: Bordadágua, Beatriz, Ahlborn, Felix, Hekker, Saskia

Institutions: Heidelberg University, Heidelberg Institute for Theoretical Studies

Language: English

Topic: Stellar, planetary, and galactic studies

Subfield: Astronomy and Astrophysics

Field: Physics and Astronomy

Domain: Physical Sciences

Open Access status: green

Funder: European Commission

Award: G4582869761