Time-dependent Fourier analysis, application to nonlinear-pulsations of stellar models

In this work a time-dependent Fourier analysis is described and applied to the study of the numerically generated hydrodynamic behavior of a stellar model. The approach yields the temporal variation of the amplitudes and phases of the various excited modes and sheds new light on the modal interaction and on the approach to the final steady pulsation. The classical radial variable stars are characterized by the fact that the growth- or decay-rates of the low-lying modes are much smaller than the pulsational frequency. This allows the authors to describe their behavior in terms of a multiperiodic signal with slowly varying amplitudes and phases