Constraints on opacities from complex asteroseismology of B-type pulsators: the $\beta$ Cephei star $\theta$ Ophiuchi

Abstract

We present results of a {\bf comprehensive} asteroseismic modelling of the $\beta$ Cephei variable $\theta$ Ophiuchi. {\bf We call these studies {\it 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, $\ell$, 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 $\theta$ Oph point substantially to preference for the OPAL data.

10 pages, 11 figures, accepted for publication in MNRAS

References in corpus (3)

• An asteroseismic study of the beta Cephei star theta Ophiuchi: constraints on global stellar parameters and core overshooting
• The two hybrid B-type pulsators: Nu Eridani and 12 Lacertae
• Asteroseismology of hybrid pulsators made possible: simultaneous MOST space photometry and ground-based spectroscopy of Gamma Peg

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