An extensive photometric study of the Blazhko RR Lyrae star RZ Lyr*

Jurcsik, J.; Sódor, Á.; Hajdu, G.; Szeidl, B.; Dózsa, Á.; Posztobányi, K.; Smitola, P.; Belucz, B.; Fehér, Virág Piroska; Kővári, Zs.; Kriskovics, L.; Kun, Emma; Molnár, L.; Nagy, I.; Vida, K.; Görög, N.

doi:10.1111/j.1365-2966.2012.20772.x

Cited by 13 publications

(13 citation statements)

References 45 publications

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“…A possible explanation might be that the changing physical parameters during the Blazhko cycle (Jurcsik et al ) temporarily fulfil the conditions required for the excitation of the other observed (radial or non‐radial) modes, whereas the chance to satisfy the excitation conditions is much smaller for the RRab stars that have stable light curves. A similar explanation has been suggested for the appearance of a peculiar bump on the descending branch of RZ Lyr in the low‐amplitude phases of its modulation (Jurcsik et al ). However, the excited additional mode of RZ Lyr is supposed to be in resonance with one of the harmonics of the main pulsation frequency, which explains why it does not appear in the Fourier spectrum as an additional frequency directly.…”

Section: Discussion and Summarysupporting

confidence: 71%

“…In the context of the Konkoly Blazhko Surveys I and II (Jurcsik et al ; Sódor et al ), we have obtained multicolour light curves of bright, northern, fundamental‐mode Blazhko RR Lyrae stars. These data have already been successfully utilized to derive the variations in the atmospheric parameters of six modulated stars (see section in Jurcsik et al , and references therein).…”

Section: Introductionmentioning

confidence: 99%

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The light-curve modulation of XY And and UZ Vir: two Blazhko RR Lyrae stars with additional frequencies

Sódor

Hajdu

Jurcsik

et al. 2012

Monthly Notices of the Royal Astronomical Society

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We present a thorough analysis of multicolour CCD observations of two modulated RRab‐type variables, XY And and UZ Vir. These Blazhko stars show relatively simple light‐curve modulation with the usual multiplet structures in their Fourier spectra. One additional, independent frequency with linear‐combination terms of the pulsation frequency is also detected in the residual spectrum of each of the two stars. The amplitude and phase relations of the triplet components are studied in detail. Most of the epoch‐independent phase differences show a slight, systematic colour dependence. However, these trends have opposite signs in the two stars. The mean values of the global physical parameters and their changes with the Blazhko phase are determined, utilizing the inverse photometric method (IPM). The modulation properties and the IPM results are compared for the two variables. The pulsation period of XY And is the shortest when its pulsation amplitude is the highest, while UZ Vir has the longest pulsation period at this phase of the modulation. Despite this contrasting behaviour, the phase relations of the variations in their mean physical parameters are similar. These results do not agree with the predictions of the Blazhko model of Stothers.

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Section: Discussion and Summarysupporting

confidence: 71%

Section: Introductionmentioning

confidence: 99%

The light-curve modulation of XY And and UZ Vir: two Blazhko RR Lyrae stars with additional frequencies

Sódor

Hajdu

Jurcsik

et al. 2012

Monthly Notices of the Royal Astronomical Society

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“…7 with fig. 11 in Jurcsik et al (2012b), we find remarkable agreement between the modulation behaviour of Z CVn and RZ Lyrae. Each parameter changes -or remains constant -very similarly.…”

Section: Sódorsupporting

confidence: 70%

A cautionary tale of interpreting O−C diagrams: period instability in a classical RR Lyr Star Z CVn mimicking as a distant companion

Skarka

Liška

Dřevěný

et al. 2017

Monthly Notices of the Royal Astronomical Society

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We present a comprehensive study of Z CVn, an RR Lyrae star that shows long-term cyclic variations of its pulsation period. A possible explanation suggested from the shape of the O−C diagram is the light travel-time effect, which we thoroughly examine. We used original photometric and spectroscopic measurements and investigated the period evolution using available maximum times spanning more than one century. If the binary hypothesis is valid, Z CVn orbits around a black hole with minimal mass of 56.5 M ⊙ on a very wide (P orbit = 78.3 years) and eccentric orbit (e = 0.63). We discuss the probability of a formation of a black hole-RR Lyrae pair and, although we found it possible, there is no observational evidence of the black hole in the direction to Z CVn. However, the main objection against the binary hypothesis is the comparison of the systemic radial velocity curve model and spectroscopic observations that clearly show that Z CVn cannot be bound in such a binary. Therefore, the variations of pulsation period are likely intrinsic to the star. This finding represents a discovery/confirmation of a new type of cyclic period changes in RR Lyrae stars. By the analysis of our photometric data, we found that the Blazhko modulation with period of 22.931 d is strongly dominant in amplitude. The strength of the phase modulation varies and is currently almost undetectable. We also estimated photometric physical parameters of Z CVn and investigated their variations during the Blazhko cycle using the Inverse Baade-Wesselink method.

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“…observing it only during Blazhko minimum where the peak-to-peak amplitude can be as low as 70 mmag. Extremely low pulsation amplitudes during Blazhko minima were recently also reported by Sódor et al (2012) for two of the RRab type stars, and the occurrence of a strong bump during Blazhko minimum was noted in RZ Lyr (Jurcsik et al 2012). In Fig.…”

Section: The V445 Lyr Data Setmentioning

confidence: 85%

The complex case of V445 Lyr observed with Kepler: two Blazhko modulations, a non-radial mode, possible triple mode RR Lyrae pulsation, and more

Guggenberger¹,

Kolenberg²,

Nemec³

et al. 2012

Monthly Notices of the Royal Astronomical Society

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Rapid and strong changes in the Blazhko modulation of RR Lyrae stars, as have recently been detected in high-precision satellite data, have become a crucial topic in finding an explanation of the long-standing mystery of the Blazhko effect. We present here an analysis of the most extreme case detected so far, the RRab star V445 Lyr (KIC 6186029) which was observed with the Kepler space mission. V445 Lyr shows very strong cycle-to-cycle changes in its Blazhko modulation, which are caused by both a secondary long-term modulation period and irregular variations. In addition to the complex Blazhko modulation, V445 Lyr also shows a rich spectrum of additional peaks in the frequency range between the fundamental pulsation and the first harmonic. Among those peaks, the second radial overtone could be identified, which, combined with a metallicity estimate of [Fe/H] = −2.0 dex from spectroscopy, allowed us to constrain the mass (0.55-0.65 M ) and luminosity (40-50 L ) of V445 Lyr through theoretical Petersen diagrams. A non-radial mode and possibly the first overtone are also excited. Furthermore, V445 Lyr shows signs of the period-doubling phenomenon and a longterm period change. A detailed Fourier analysis along with a study of the O − C variation of V445 Lyr is presented, and the origin of the additional peaks and possible causes of the changes in the Blazhko modulation are discussed. The results are then put into context with those of the only other star with a variable Blazhko effect for which a long enough set of high-precision continuous satellite data has been published so far, the CoRoT star 105288363.

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An extensive photometric study of the Blazhko RR Lyrae star RZ Lyr*

Cited by 13 publications

References 45 publications

The light-curve modulation of XY And and UZ Vir: two Blazhko RR Lyrae stars with additional frequencies

The light-curve modulation of XY And and UZ Vir: two Blazhko RR Lyrae stars with additional frequencies

A cautionary tale of interpreting O−C diagrams: period instability in a classical RR Lyr Star Z CVn mimicking as a distant companion

The complex case of V445 Lyr observed with Kepler: two Blazhko modulations, a non-radial mode, possible triple mode RR Lyrae pulsation, and more

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