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A- and B-type star pulsations in the Kepler and CoRoT era: theoretical considerations

Among A-type main-sequence variables, pulsations of $δ$ Sct and $γ$ Dor variables are driven in the He II ionization zone, while H-ionization zone and strong magnetic fields seem to play roles in the excitation of high-order p-modes in rapidly oscillating Ap (roAp) stars. Pulsations in B-type variables, $β$ Cephei and slowly pulsating B (SPB) stars are excited by the $κ$-mechanism at the Fe-opacity bump at $T\approx 2\times10^5$K. In addition, the strange-mode instability seems responsible for the excitation of pulsations in luminous AB-supergiants ($α$ Cygni variables). We discuss excitation mechanisms for pulsations in A- and B-type variables stars.