The Kepler RR Lyrae SC Data Set: Period Variation and Blazhko Effect

TL;DR

This study analyzes extensive Kepler data on RR Lyrae stars, revealing detailed period variations and Blazhko effect dynamics over multiple cycles, including changes in pulsation and modulation periods.

Contribution

It provides a comprehensive analysis of RR Lyrae period variability and Blazhko modulation using high-precision Kepler data, highlighting new insights into their dynamic behavior.

Findings

Pulsation period varies within each Blazhko cycle.

Blazhko period itself changes over the 4-year modulation.

Rapid increases in Blazhko period occur at cycle starts.

Abstract

We study the 1.28 million short cadence {\it Kepler} data points (Q5-Q14) for RR Lyrae covering 24 cycles of the Blazhko variation, and more than one half of the 4-year modulation of the Blazhko variation. This very rich data set clearly shows variability of the 0.5667 day pulsation period (from 0.5655 to 0.5685 day) with each Blazhko cycle, as well as a variation of the Blazhko period itself (from 39.2 days at amplitude maximum to 38.4 days at amplitude minimum) during the 4 year modulation, as well as a rapid increase in Blazhko period as the new cycle commences.