The Blazhko phenomenon

TL;DR

This review summarizes the current observational understanding of the Blazhko effect in RR Lyrae stars, discusses the failure of existing explanations, and explores new research directions including advanced modeling and incidence rate estimates.

Contribution

It provides new estimates of the true incidence rate of Blazhko stars in the Large Magellanic Cloud and tests on the impact of aspect angle on modulation amplitudes.

Findings

Estimated the true incidence rate of Blazhko stars in the LMC.

Tested the effect of aspect angle on modulation amplitudes.

Reviewed the failure of current models to explain the Blazhko effect.

Abstract

In spite of the accumulating high quality data on RR Lyrae stars, the underlying cause of the (quasi)periodic light curve modulation (the so-called Blazhko effect) of these objects remains as mysterious as it was more than hundred years ago when the first RR Lyrae observations were made. In this review we briefly summarize the current observational status of the Blazhko stars, discuss the failure of all currently available ideas attempting to explain the Blazhko effect and finally, we contemplate on various avenues, including massive 2-3D modeling to make progress. Somewhat unconventionally to a review, we present some new results, including the estimate of the true incidence rate of the fundamental mode Blazhko stars in the Large Magellanic Cloud, and tests concerning the effect of the aspect angle on the observed distribution of the modulation amplitudes for Blazhko models involving nonradial modes.