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SS Cygni-A Nonlinear Look at 100 Years of AAVSO Data

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N. Jevtic

Physics Department, University of Connecticut, 2152 Hillside Rd. U-3046, Storrs, CT 06269

Janet A. Mattei

AAVSO, 25 Birch Street, Cambridge, MA 02138

J. S. Schweitzer

Physics Department, University of Connecticut, 2152 Hillside Rd. U-3046, Storrs, CT 06269

Presented at the 91st Annual Meeting of the AAVSO, October 2002

Abstract  A full nonlinear time series analysis was conducted of ~100 years of visual observations from the American Association of Variable Star Observers (AAVSO) International Database for the cataclysmic variable SS Cygni. Intensity was obtained from the AAVSO magnitude data using: F(L) = 10 ^{- (0.4 (visual magnitude) + 8.43)}. Intensity is a “better” dynamical variable because energy couples all the active degrees of freedom. An intensity phase space portrait was reconstructed in 3-D using time delay coordinates. A series of Poincare sections was obtained. The Poincare section return times suggest a long-term periodicity of ~52 years. We also obtained the times between outbursts in a more traditional manner, the outbursts being defined with respect to a baseline determined by the adjacent quiescent sections. Excellent agreement was found between these two approaches. An observed region of discrepancy is for an interval containing many lower amplitude shorter outbursts. Earlier reports using the O-C method indicated a long-term variation on the order of at least 100 years, thus it remains to be seen whether we are detecting a fundamental frequency or its first harmonic.

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