Interior rotation modelling of the β Cep pulsator HD 192575 including multiplet asymmetries

¹ Institute of Astronomy, KU Leuven, Celestijnenlaan 200D, 3001 Leuven, Belgium
² School of Mathematics, Statistics and Physics, Newcastle University, Newcastle upon Tyne, NE1 7RU, UK
³ Institute of Science and Technology Austria (ISTA), Am Campus 1, Klosterneuburg, Austria
⁴ Center for Astrophysics | Harvard & Smithsonian, 60 Garden Street, Cambridge, MA, 02138, USA
⁵ Université Paris-Saclay, Université Paris Cité, CEA, CNRS, AIM, 91191 Gif-sur-Yvette, France
⁶ Department of Astrophysics, IMAPP, Radboud University Nijmegen, PO Box 9010 6500 GL Nijmegen, The Netherlands
⁷ Max Planck Institute for Astronomy, Königstuhl 17, 69117 Heidelberg, Germany

^⋆ Corresponding author: vincent.vanlaer@kuleuven.be

Received: 5 November 2024
Accepted: 9 July 2025

Abstract

Context. Rotation plays an important role in stellar evolution. However, the mechanisms behind the transport of angular momentum in stars at various stages of their evolution are not well understood. To improve our understanding of these processes, it is necessary to measure and validate the internal rotation profiles of stars across different stages of evolution and mass regimes.

Aims. Our aim is to constrain the internal rotation profile of the 12-M_⊙ β Cep pulsator HD 192575 from the observed pulsational multiplets and the asymmetries of their component frequencies.

Methods. We updated the forward asteroseismic modelling of HD 192575 based on new TESS observations. We inverted the rotation profile from the symmetric part of the splittings and computed the multiplet asymmetries due to the Coriolis force and stellar deformation, which we treated perturbatively. We compared the computed asymmetries with the observed asymmetries.

Results. Our new forward asteroseismic modelling is in agreement with previous results but with increased uncertainties, partially due to increased frequency precision, which required us to relax certain constraints. Ambiguity in the mode identification is the main source of the uncertainty, which also affects the inferred rotation profiles. Almost all acceptable rotation profiles occur in the regime below 0.4 d⁻¹ and favour weak radial differential rotation, with a ratio of core to envelope rotation of less than 2. We find that the quality of the match between the observed and theoretically predicted mode asymmetries is strongly dependent on the mode identification and the internal structure of the star.

Conclusions. Our results offer the first detailed rotation inversion for a β Cep pulsator. They show that the rotation profile and the mode asymmetries provide a valuable tool for further constraining the evolutionary properties of HD 192575, and in particular the details of angular momentum transport in massive stars.