Long-term photometric behaviour of XZ Dra
Binarity or magnetic cycle of a Blazhko-type RRab star
Konkoly Observatory of the Hungarian Academy of Sciences, PO Box 67, 1525 Budapest, Hungary e-mail: jurcsik,benko,email@example.com
Corresponding author: J. Jurcsik, firstname.lastname@example.org
Accepted: 16 July 2002
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 exhibits cyclic, but not strictly regular variations with ≈7200 d period. The Blazhko period (≈76 d) seems to follow the observed period changes of the fundamental mode pulsation with gradient. A 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 a magnetic cycle is raised.
Key words: stars: individual: XZ Dra / stars: variables: RR Lyr / stars: oscillations / stars: horizontal-branch / techniques: photometric / techniques: radial velocities
© ESO, 2002