Nonlinear Dynamics of RRc Lyrae Stars

Abstract

In this work we consider the nonlinear dynamics of RRc Lyrae variable stars, using intensity data from the Kepler space telescope. RRc Lyrae variables are shown to exhibit rich nonlinear dynamical behavior, including strange nonchaotic and quasiperiodic behaviors. We examine the intensity variations (or light curves) of four confirmed RRc Lyrae stars (KIC 4064484, 5520878, 8832417, and 9453114) in the Kepler field of view. Earlier work has classified two of the four stars as quasiperiodic with noise contamination and two as exhibiting strange nonchaotic dynamics George et al. (Nonlinear Dyn 89(1):465, 2017). We explore the recurrence network properties and bicoherence of these stars. We find the groups of stars that show the same dynamical behavior also show similar nonlinear properties. We also do a comparison of the metallicities and pulsation periods of these stars to their nonlinear properties. Our results support the existence of two distinct subcategories of RRc Lyrae stars and indicate a link between the nonlinear and astrophysical properties of RRc Lyrae variable stars.