An excitation mechanism for pulsations in beta CEP stars.

Abstract

view Abstract Citations (62) References (21) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS An excitation mechanism for pulsations in Beta Cephei stars. Osaki, Y. Abstract A mechanism which might be responsible for the excitation of pulsations in Cephei stars is proposed in which an eigenmode of the nonradial oscillations of the whole star resonates with the overstable convection in the rapidly spinning core of a massive star. The degeneracy of the two frequencies is found to be possible only in the late stages of core hydrogen burning in massive stars. The equations for adiabatic, nonradial oscillations have been solved for a realistic stellar model, and it is shown that the eigenfunction of the f-mode has large amplitudes only in the convective core and near the surface, which is a situation favorable to the operation of this mechanism. The resonant excitation of a nonradial oscillation by oscillatory convection has been formulated on the basis of Lighthill's method. The coupling occurs linearly in the presence of rotation, and a crude estimate is given for the amplitude of the excited oscillation. The most likely mode excited by this mechanism is a sectoral mode, which is a wave traveling around the equator in the same direction as the rotation; and this seems to agree with observations. Subject headings: Cephei stars - interiors, stellar - pulsation Publication: The Astrophysical Journal Pub Date: May 1974 DOI: 10.1086/152825 Bibcode: 1974ApJ...189..469O full text sources ADS | data products SIMBAD (1)