Blazhko effect in Cepheids and RR Lyrae stars

Research output: Chapter in Book/Report/Conference proceedingConference contribution

3 Citations (Scopus)


The Blazhko effect is the conspicuous amplitude and phase modulation of the pulsation of RR Lyrae stars that was discovered in the early 20th century. The field of study of this mysterious modulation has recently been invigorated thanks to the space photometric missions providing long, uninterrupted, ultra-precise time-series data. In this paper I give a brief overview of the new observational findings related to the Blazhko effect, such as extreme modulations, irregular modulation cycles and additional periodicities. I argue that these findings together with dedicated ground-based efforts provide us now with a fairly complete picture and a good starting point to theoretical investigations. Indeed, new, unpredicted dynamical phenomena have been discovered in Blazhko RR Lyrae stars, such as period doubling, high-order resonances, three-mode pulsation and low-dimensional chaos. These led to the proposal of a new explanation to this century-old enigma, namely a high-order resonance between radial modes. Along these lines I present the latest efforts and advances from the theoretical point of view. Lastly, amplitude variations in Cepheids are discussed.

Original languageEnglish
Title of host publicationPrecision Asteroseismology
EditorsJoyce Guzik, William Chaplin, William Chaplin, Gerald Handler, Andrzej Pigulski
Number of pages8
Publication statusPublished - Mar 3 2014

Publication series

NameProceedings of the International Astronomical Union
ISSN (Print)1743-9213
ISSN (Electronic)1743-9221



  • Blazhko effect
  • Kepler
  • V445 Lyr
  • V473 Lyr
  • hydrodynamics
  • pulsation
  • stars: individual: RR Lyr
  • stars: variables: Cepheids
  • stars: variables: RR Lyrae
  • α UMi

ASJC Scopus subject areas

  • Medicine (miscellaneous)
  • Astronomy and Astrophysics
  • Nutrition and Dietetics
  • Public Health, Environmental and Occupational Health
  • Space and Planetary Science

Cite this

Szabó, R. (2014). Blazhko effect in Cepheids and RR Lyrae stars. In J. Guzik, W. Chaplin, W. Chaplin, G. Handler, & A. Pigulski (Eds.), Precision Asteroseismology (S301 ed., pp. 241-248). (Proceedings of the International Astronomical Union; Vol. 9, No. S301).