Blazhko effect

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The Blazhko effect, which is sometimes called long-period modulation, is a variation in period and amplitude in RR Lyrae type variable stars. It was first observed by Sergey Blazhko in 1907 in the star RW Draconis.[1] The recent Kepler (spacecraft) observations caught the community by surprise. [2] In addition to the modulations the observations showed cycle to cycle alternations in the light curves.

The physics behind the Blazhko effect is currently still a matter of debate, with there being three primary hypotheses. In the first, referred to as the resonance model, the cause of the modulation is a non-linear resonance among either the fundamental or the first overtone pulsation mode of the star and a higher mode. [3] [4] The second, known as the magnetic model, assumes the variation to be caused by the magnetic field being inclined to the rotational axis, deforming the main radial mode. [5] The third model assumes that cycles in the convection cause the alternations and the modulations. [6]

References[edit]

  1. ^ Horace A. Smith (2004). RR Lyrae Stars. Cambridge University Press. p. 103. ISBN 0-521-54817-9. 
  2. ^ R. Szabo et al. , 2010, Monthly Notices of the Royal Astronomical Society, Vol. 409, p. 1244
  3. ^ Z. Kollath, L. Molnar & R. Szabo, 2011, Monthly Notices of the Royal Astronomical Society, Vol 414 p. 1111; (also http://xxx.lanl.gov/abs/1102.0157)
  4. ^ J. R. Buchler & Z. Kollath, 2011, Astrophysical Journal, Vol 731, p. 24 (also http://xxx.lanl.gov/abs/1101.1502)
  5. ^ Katrien Kolenberg (2008). "Explanations for the Blazhko effect in RR Lyrae stars". The Blazhko Project. Retrieved 2008-12-17. 
  6. ^ Stothers, R.B. 2010, Publications of the Astronomical Society of the Pacific Vol. 122, p. 536

External links[edit]