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Low-dimensional chaos in stellar pulsations is the current interpretation of an established phenomenon. The light curves of intrinsic variable stars with large amplitudes have been known for centuries to exhibit behavior that goes from extreme regularity, as for the classical Cepheids and the RR Lyrae stars, to extreme irregularity, as for the so-called Irregular variables. In the Population II stars this irregularity gradually increases from the low period W Virginis variables through the RV Tauri variables into the regime of the semiregular variables. ==Regular behavior of the Cepheids== The regular behavior of the Cepheids has been successfully modeled with numerical hydrodynamics since the 1960s〔Christy, R. F., 1964, ''The Calculation of Stellar Pulsation'', Reviews of Modern Physics 36, 555 "()"〕 ,〔Cox, A. N., Brownlee, R. R., Eilers, D. D., 1966 ''Time-Dependent Method for Computation of Radiation Diffusion and Hydro-Dynamics'', Astrophysical Journal, 144, 1024 "()"〕 and from a theoretical point of view it is easily understood as due to the presence of center manifold which arises because of the weakly dissipative nature of the dynamical system.〔Buchler, J.R. 1993, ''A Dynamical Systems Approach to Nonlinear Stellar Pulsations'', in ''Nonlinear Phenomena in Stellar Variability'', Eds. M. Takeuti & J.R. Buchler, Dordrecht: Kluwer Publishers, reprinted from 1993, Astrophysics and Space Science, 210, 1–31. "()"〕 This, and the fact that the pulsations are weakly nonlinear, allows a description of the system in terms of amplitude equations〔Spiegel, E. A., ''Cosmic Arrhythmias'' in ''Chaos in Astrophysics'', NATO ASI Ser. C, Vol. 161, eds. J. R. Buchler J. M. Perdang \& E. A. Spiegel, (Dordrecht : Reidel)〕 〔Buchler, J.R. & Goupil, M.J. 1984, ''Amplitude Equations for Nonadiabatic, Nonlinear Stellar Pulsators, I. The Formalism'', Astrophysical Journal 279, 394–400, "()"〕 and a construction of the bifurcation diagram (see also bifurcation theory) of the possible types of pulsation (or limit cycles), such fundamental mode pulsation, first or second overtone pulsation, or more complicated, double-mode pulsations in which several modes are excited with constant amplitudes. The boundaries of the instability strip where pulsation sets in during the star's evolution correspond to a Hopf bifurcation. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Low-dimensional chaos in stellar pulsations」の詳細全文を読む スポンサード リンク
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