Constraints on opacities from complex asteroseismology of B-type pulsators: the β Cephei star θ Ophiuchi

Original · EN

We present results of a comprehensive asteroseismic modelling of the β Cephei variable θ Ophiuchi. We call these studies complex asteroseismology because our goal is to reproduce both pulsational frequencies as well as corresponding values of a complex, nonadiabatic parameter, f, defined by the radiative flux perturbation. To this end, we apply the method of simultaneous determination of the spherical harmonic degree, ℓ, of excited pulsational mode and the corresponding nonadiabatic f parameter from combined multicolour photometry and radial velocity data. Using both the OP and OPAL opacity data, we find a family of seismic models which reproduce the radial and dipole centroid mode frequencies, as well as the f parameter associated with the radial mode. Adding the nonadiabatic parameter to seismic modelling of the B-type main sequence pulsators yields very strong constraints on stellar opacities. In particular, only with one source of opacities it is possible to agree the empirical values of f with their theoretical counterparts. Our results for θ Oph point substantially to preference for the OPAL data.