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