Department of Physics and Astronomy: Publications and Other Research
Document Type
Article
Date of this Version
4-1-1980
Citation
THE ASTROPHYSICAL JOURNAL, 237: 175-186, 1980 April 1
Abstract
The iterative nonlinear pulsation theory is extended to the bimodal case, and a series of equations derived which are complete to second order. Solutions to these equations are obtained for a number of long-period double-mode Cepheid models in the vicinity of the interaction resonance Ѡl + Ѡ0 = Ѡ3 and the harmonic resonance P2/P0 = 0.5. We show that the resonant second-order amplitudes and phases change abruptly as the center of the resonance is approached. In addition, it is demonstrated that, inward of the hydrogen ionization zone, the amplitudes strongly resemble the linear eigenfunctions to which they are resonantly linked. Thus the resonances are shown to have spatial as well as temporal content. Due to nonadiabatic effects the second-order terms are particularly strong in the H I ionization zone, a circumstance which suggests that this region could play an important role in determining limiting-amplitude behavior.
Comments
Copyright 1980 The American Astronomical Society. All rights reserved.