Blazhko stars: Always distorted?

Jurcsik, J.; Benkő, J. M.; Szeidl, B.

doi:10.1051/0004-6361:20020654

Cited by 33 publications

(34 citation statements)

References 17 publications

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“…Thus the four-year cycle of RR Lyrae may also indicate a similar explanation (Detre & Szeidl 1973). According to recent results (Jurcsik et al 2002) the light curves of RR Lyrae correspond to that of non-Blazhko RRab stars during the minimal phase of the four-year cycle, when the amplitude of the modulation is small. This suggests that if the oblique magnetic rotator-pulsator model, which describes the observed modulation of the light curve, is valid, then the diminution of the modulation indicates weakening in the global magnetic field strengths, consequently resulting in normal type, undisturbed light changes.…”

Section: Magnetic Cyclesmentioning

confidence: 76%

Long-term photometric behaviour of XZ Dra

Jurcsik¹,

Benkő²,

Szeidl³

2002

A&A

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Abstract. The extended photometry available for XZ Dra, a Blazhko-type RR Lyrae star, makes it possible to study its longterm 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 dP B /dP 0 = 7.7 × 10 4 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.

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Section: Magnetic Cyclesmentioning

confidence: 76%

Long-term photometric behaviour of XZ Dra

Jurcsik¹,

Benkő²,

Szeidl³

2002

A&A

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“…These results seem to indicate that the Blazhko effect is connected with a mechanism which tends to suppress the normal pulsational features of the star (Szeidl 1976).ȃ An interesting study in this respect was carried out by Jurcsik et al (2002a), through a comparison of the light and radial velocity amplitudes as well as the light curve shapes (using Fourier parameters) between Blazhko stars and so-called "normal", non-modulated, RR Lyrae stars. They concluded that, for Blazhko stars with large amplitude modulation, there is no Blazhko phase that seems to be wellmatched with that of a non-modulated RRab star.…”

Section: Explanations For the Blazhko Effectmentioning

confidence: 90%

The Blazhko effect of RR Lyrae in 2003-2004

Kolenberg

Smith

Gazeas

et al. 2006

A&A

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Aims. Extensive photometry of RR Lyr was obtained over a 421-day interval in 2003-2004, covering more than 10 Blazhko cycles in a multisite campaign. The length and density of this data set allow for a detailed analysis. Methods. We used Fourier techniques to study RR Lyr's behavior over the pulsation and the Blazhko cycle. We propose a twofrequency model for decomposing the frequency spectrum. Results. The light variations were fitted with the main radial frequency, its harmonics up to 11th order, and the detected triplet frequencies. No significant quintuplet components were found in the frequency spectrum. Given the total time span of the measurements, we can now unambiguously conclude that the Blazhko period has become notably shorter than the previously known value of 40.8 days, whereas the main pulsation period remained roughly the same. Changes in the modulation period have been reported for other well-studied Blazhko variables. They challenge the explanations for the Blazhko effect which link the modulation period directly to the rotation period. The new photometry reveals an interval in the pulsation cycle of RR Lyr during which the star's intensity barely changes over the Blazhko cycle. This interval occurs during the infalling motion and between the supposed phases of the early and the main shock. The data also permit a more detailed study of the light curve shape at different phases in the Blazhko period through Fourier parameters.

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“…(2). We stress that this is a different procedure from that used by Jurcsik et al (2002), who have evaluated the Fourier parameters of the snapshot lightcurves at various phases of the beat (Blazhko) period. As a result, their parameters are time dependent.…”

Section: Blazhko Variables and Metallicitymentioning

confidence: 99%

Fourier decomposition and frequency analysis of the pulsating stars with $P < $ 1 d in the OGLE database

Moskalik

Poretti

2003

A&A

101

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Abstract. We present the results of a systematic search for multiperiodic pulsators among the Galactic Bulge RR Lyrae stars of the OGLE-1 sample. We identify one "canonical" double-mode variable (RRd star) pulsating in two radial modes. In 38 stars we detect secondary periodicities very close to the primary pulsation frequency. This type of multiperiodic variables constitute ∼23% of RRab and ∼5% of RRc population of the Bulge. With the observed period ratios of 0.95−1.02 the secondary periods must correspond to nonradial modes of oscillation. Their beating with the primary (radial) pulsation leads to a long-term amplitude and phase modulation, known as the Blazhko effect. The Blazhko RRab variables occur more frequently in the Galactic Bulge than in the LMC. The opposite tendency is seen in case of the RRd stars. The differences of incidence rates are most likely caused by different metallicity of the two populations. We discuss pulsation properties of the OGLE-1 Blazhko stars and compare them with predictions of theoretical models. We argue, that the oblique magnetic pulsator model of Shibahashi (2000) cannot account for the observations and should be ruled out.

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Blazhko stars: Always distorted?

Cited by 33 publications

References 17 publications

Long-term photometric behaviour of XZ Dra

Long-term photometric behaviour of XZ Dra

The Blazhko effect of RR Lyrae in 2003-2004

Fourier decomposition and frequency analysis of the pulsating stars with $P < $ 1 d in the OGLE database

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