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N. Jevtic (Physics Dept., University of Connecticut), J.A. Mattei (AAVSO), J.S. Schweitzer (Physics Dept., University of Connecticut)
A full nonlinear time series analysis was conducted of ~100 years of AAVSO data for SS Cygni. The missing gaps in the data were bridged by linear interpolation. Both magnitude and intensity data, F(\Lambda), where F(\Lambda) = 10 - (0.4 (visual magnitude) + 8.43), were analyzed. The magnitude data gave results consistent with noise in all steps of the analysis except the Poincare section return times where some structure was observed. This prompted an analysis of the intensity curves because intensity, i.e. energy, couples active degrees of freedom better and as such is a ``better" dynamical variable. The average mutual information was used to obtain the optimal time delay of 40 days and false nearest neighbors were probed for the low limit on the dimension of the reconstruction. A phase space portrait was reconstructed and was tested for local correlation dimension. In 3D, a Poincare section was obtained. The Poincare section return times indicated a long-term periodicity of ~52 years. Earlier reports were of a long-term variation on the order of 100 years. In an attempt to understand our result, an analysis of the burst energy was conducted by integrating burst area with respect to the baseline defined by adjacent quiescent sections. Excellent agreement was found between the variation of the interval between bursts and the variation in the Poincare section return times. The significance of this result for the better understanding of the dynamics of the system is currently being evaluated.
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Bulletin of the American Astronomical Society, 34
© 2002. The American Astronomical Soceity.