Simple nonlinear models suggest variable star universality

TL;DR

This paper explores how simple nonlinear models can explain the universal features observed in variable star luminosity variations, linking complex stellar behaviors to fundamental nonlinear phenomena.

Contribution

It proposes that features of variable star dynamics are manifestations of universal nonlinear phenomena, supported by phenomenological models connecting observations to fractal spectra.

Findings

Identification of quasiperiodic luminosity variations with golden ratio frequencies

Evidence of power-law scaling in secondary frequencies suggesting strange nonchaotic dynamics

Connection between observed stellar behaviors and simple nonlinear system models

Abstract

Dramatically improved data from observatories like the CoRoT and Kepler spacecraft have recently facilitated nonlinear time series analysis and phenomenological modeling of variable stars, including the search for strange (aka fractal) or chaotic dynamics. We recently argued [Lindner et al., Phys. Rev. Lett. 114 (2015) 054101] that the Kepler 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 exponent near -1.5, suggesting strange nonchaotic dynamics and singular spectra. Here we use a series of phenomenological models to make plausible the connection between golden stars and fractal spectra. We thereby suggest that at least some features of variable star dynamics reflect universal nonlinear phenomena common to even simple systems.