Rotational and magnetic splitting in the beta-Cep pulsator HD 192575
Abstract
The theory of angular momentum transport leads to inconsistencies with internal rotation frequencies measured through asteroseismology for a significant number of stars. Various mechanisms such as internal gravity waves or magnetic fields have been proposed to solve this discrepancy. However, these proposals need to be validated with observations. Of particular importance are stars with observed constraints on internal structure, internal rotation profile and internal magnetic field properties. Asteroseismology can provide these constraints through the analysis of the asymmetries of rotationally split multiplets. In this context HD 192575 is a unique massivecalibration star. It has one of the richest frequency spectra of all known supernova progenitors. Both gravity-mode and pressure-mode rotationally split multiplets have been detected, with one of the gravity-mode multiplets potentially being split by magnetism as well. We perform a rotation inversion and verify whether the contribution of rotation to the asymmetries matches with the observations. Our rotation inversions deliver the theoretical asymmetries are roughly consistent with the observed asymmetries. Further, we show that the richest gravity-mode multiplet is consistent with being magnetically split. We derive constraints on the magnetic field properties. The remaining differences between the modelled asymmetries and the observations provide valuable insights and constraints for further modelling efforts of thisevolved massive star.