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Strange Nonchaotic Stars

Physics/Astro Auditorium

John Lindner (The College of Wooster)

May 11 @ 4:00 PM - 5:00 PM

My collaboration recently argued that Kepler space telescope data includes “golden” stars whose luminosities vary quasiperiodically, with two frequencies nearly in the golden ratio, and whose secondary frequencies exhibit power-law scaling with an exponent near -1.5, suggesting strange nonchaotic dynamics. Fractal state space structure without sensitive dependence on initial conditions is a distinctive but underappreciated dynamics between order and chaos. While familiar strange chaotic attractors famously exhibit complicated and unrepeatable dynamics, strange nonchaotic attractors exhibit complicated but predictable dynamics. In this talk, I describe how spectral scaling can distinguish between different sub classes of RR Lyrae variable stars in both Kepler and Optical Gravitational Lensing Experiment (OGLE) photometry. I then use a series of phenomenological models to make plausible the connection between golden stars and fractal spectra. I thereby suggest that some features of variable star dynamics may reflect universal nonlinear phenomena common to even simple systems.