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Strange Nonchaotic Stars

Physics/Astro Auditorium

John Lindner (The College of Wooster)

May 11, 2017 @ 4:00 PM - 5:00 PM

Click here to view Panopto video recording of this talk.

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.