Nonlinear pulsations of a very luminous star

Abstract

The radial nonlinear pulsations of a model withM=0.8M _⊙,M _bol=−6 mag andT _eff=5500 K have been studied. The pulsations are shown to exist in the form of the standing wave only in the innermost layers withR<0.2R _ph. In the outer layers, the standing wave transforms into running waves, the frequency of which decreases with an increasingR. the pulsation period at the photosphere is found to be twice as long as the pulsation period atR<0.2R _ph. The difference between the pulsation periods causes alternation of deep and shallow minima in the temporal dependences of the kinetic energy and radii and can be used to explain the nature of RV Tau variables. It is shown that at the distanceR>3R _ph, the time-independent mass flux caused by shocks takes place. The rate of mass loss is found to beM∼10⁻⁴ M _⊙ yr⁻¹.