Seismology of β Cephei Stars: Differentially Rotating Models for Interpreting the Oscillation Spectrum of ν Eridani
Résumé
A method for the asteroseismic analysis of β Cephei stars is presented and applied to the star ν Eridani. The method is based on the analysis of rotational splittings and their asymmetries using differentially rotating asteroseismic models. Models with masses around 7.13 M sun, and ages around 14.9 Myr, were found to fit better in 10 of the 14 observed frequencies, which were identified as the fundamental radial mode and the three ell = 1 triplets g1, p1, and p2. The splittings and aymmetries found for these modes recover those provided in the literature, except for p2. For this last mode, all its non-axysimmetric components are predicted by the models. Moreover, opposite signs of the observed and predicted splitting asymmetries are found. If identification is confirmed, this can be a very interesting source of information about the internal rotation profile, in particular in the outer regions of the star. In general, the seismic models that include a description for shellular rotation yield slightly better results as compared with those given by uniformly rotating models. Furthermore, we show that asymmetries are quite dependent on the overshooting of the convective core, which makes the present technique suitable for testing the theories describing the angular momentum redistribution and chemical mixing due to rotationally induced turbulence.