Multimode Radiative beta Cephei and delta Cephei Models

Copernicus Astronomical Center, Bartycka 18, 00-716 Warsaw, Poland

Abstract

As a by-product of β Cephei and δ Cephei radiative model surveys we have found interesting cases of multimode pulsation. In case of β Cephei stars, we found two multimode domains with two or three modes being involved. The origin of the multimode pulsation can be traced to one of the two different mechanisms: either to the non-resonant coupling of the two excited modes (double-mode pulsation) or to the 2ω₁ ω₀ + ω₂ parametric resonance (triple-mode pulsation). In case of δ Cephei models, a triple-mode pulsation domain, connected with the 2:1 resonance, 2ω₀ ω₂, is found. These models are of theoretical interest only, since they do not obey a proper mass-luminosity relation.