Long-term photometric behaviour of XZ Dra Binarity or magnetic cycle of a Blazhko type RRab star

Abstract

The extended photometry available for XZ Dra, a Blazhko type RR Lyrae star, makes it possible to study its long-term behavior. It is shown that its pulsation period exhibit cyclic, but not strictly regular variations with approx. 7200 d period. The Blazhko period (approx. 76 d) seems to follow the observed period changes of the fundamental mode pulsation with dP_B/dP_0=7.7 x 10^4 gradient. Binary model cannot explain this order of period change of the Blazhko modulation, nevertheless it can be brought into agreement with the O-C data of the pulsation. The possibility of occurrence of magnetic cycle is raised.

13 pages, 11 figures (submitted to A&A)

References in corpus (3)

• Does the Sun Shrink with Increasing Magnetic Activity?
• Blazhko stars: always distorted?
• Periodicities in data observed during the minimum and the rising phase of solar cycle 23; years 1996 - 1999

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• Known Galactic field Blazhko stars
• The all-sky GEOS RR Lyr survey with the TAROT telescopes. Analysis of the Blazhko effect
• Studies of RR Lyrae Variables in Binary Systems. I.: Evidence of a Trimodal Companion Mass Distribution
• The Blazhko behaviour of RR Geminorum II -- long-term photometric results
• A first-overtone RR Lyrae star with cyclic period changes
• The Blazhko behavior of RV UMa