Asteroseismology of the β Cephei star ν Eridani: interpretation and applications of the oscillation spectrum

The oscillation spectrum of ν Eri is the richest known for any variable of the β Cephei type. We interpret the spectrum in terms of normal mode excitation and construct seismic models of the star. The frequency data combined with data on mean colours set the upper limit on the extent of overshooting from the convective core. We use data on rotational splitting of two dipole (ℓ= 1) modes (g1 and p1) to infer properties of the internal rotation rate. Adopting a plausible hypothesis of nearly uniform rotation in the envelope and increasing rotation rate in the μ-gradient zone, we find that the mean rotation rate in this zone is about three times faster than in the envelope. In our standard model only the modes in the middle part of the oscillation spectrum are unstable. To account for excitation of a possible high-order g mode at ν= 0.43 cd−1 as well as p modes at ν > 6 cd−1 we have to invoke an overabundance of Fe in the driving zone.