Nonlinear dynamical analysis of the Blazhko effect with the Kepler space telescope: the case of V783 Cyg

TL;DR

This study investigates the nonlinear dynamics of the Blazhko effect in the RR Lyrae star V783 Cyg using Kepler data, but technical artifacts hinder definitive chaos detection, highlighting the need for longer or higher-quality observations.

Contribution

It applies nonlinear dynamical analysis techniques to Kepler data of V783 Cyg, revealing the challenges posed by data artifacts in detecting chaos in stellar modulation.

Findings

Chaotic signals can fit the modulation curves but are affected by data artifacts.

Instrumental and processing effects can mimic or obscure true chaos.

Four-year Kepler data is insufficient for conclusive nonlinear dynamical analysis.

Abstract

We present a detailed nonlinear dynamical investigation of the Blazhko modulation of the Kepler RR Lyrae star V783 Cyg (KIC 5559631). We used different techniques to produce modulation curves, including the determination of amplitude maxima, the O-C diagram and the analytical function method. We were able to fit the modulation curves with chaotic signals with the global flow reconstruction method. However, when we investigated the effects of instrumental and data processing artefacts, we found that the chaotic nature of the modulation can not be proved because of the technical problems of data stitching, detrending and sparse sampling. Moreover, we found that a considerable part of the detected cycle-to-cycle variation of the modulation may originate from these effects. According to our results, even the four-year-long, unprecedented Kepler space photometry of V783 Cyg is too short for a reliable nonlinear dynamical analysis aiming at the detection of chaos from the Blazhko modulation. We estimate that two other stars could be suitable for similar analysis in the Kepler sample and in the future TESS and PLATO may provide additional candidates.