CoRoT light curves of RR Lyrae stars

Poretti, E.; Paparó, M.; Deleuil, M.; Chadid, M.; Kolenberg, K.; Szabo, Robert M.; Benkő, J. M.; Chapellier, E.; Guggenberger, E.; Borgne, J. F. Le; Rostagni, F.; Trinquet, H.; Auvergne, M.; Baglin, A.; Sarro, L. M.; Weiß, W. W.

doi:10.1051/0004-6361/201014941

Cited by 48 publications

(61 citation statements)

References 37 publications

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“…Additional modes, small, mmagrange signals in the Fourier-spectra, outside the usual patterns, were observed in all classes: RRab (Poretti et al 2010;Benkő et al 2010;Guggenberger et al 2011Guggenberger et al , 2012, RRc (Moskalik et al 2013) and RRd stars (Gruberbauer et al 2007;Chadid 2012). They were detected in ground-based, multicolor photometry as well (Sódor et al 2012).…”

Section: Additional Modesmentioning

confidence: 93%

New results in RR Lyrae modeling: Convective cycles, additional modes and more

et al. 2012

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Recent theoretical and observational findings breathed new life into the field of RR Lyrae stars. The ever more precise and complete measurements of the space asteroseismology missions revealed new details, such as the period doubling and the presence of the additional modes in the stars. Theoretical work also flourished: period doubling was explained and an additional mode has been detected in hydrodynamic models as well. Although the most intriguing mystery, the Blazhko-effect has remained unsolved, new findings indicate that the convective cycle model can be effectively ruled out for short-and medium-period modulations. On the other hand, the plausibility of the radial resonance model is increasing, as more and more resonances are detected both in models and stars.

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Section: Additional Modesmentioning

confidence: 93%

New results in RR Lyrae modeling: Convective cycles, additional modes and more

et al. 2012

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“…In 2009, Le Borgne & Klotz, using in O-C observations of light maxima, confirmed for RR Lyr that the pulsation period changes with a periodicity equal to the Blazhko period. Poretti et al (2010) showed that both light amplitude and pulsation period of the Blazhko star CoRoT 101128793 vary in the Blazhko period. Guggenberger et al (2011) found strong changes in the Blazhko period, both in magnitude of the maximum and minimum light and in the phase of the bump feature, for CoRoT ID 105288363.…”

Section: Variation Of the Pulsation Parameters During The Blazhko Cyclementioning

confidence: 99%

Atmospheric dynamics in RR Lyrae stars

Gillet

2013

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Context. Discovered in 1907, the Blazhko effect is a modulation of the light variations of about half of the RR Lyr stars. It has remained unexplained for over 100 years, despite more than a dozen proposed explanations. Today it represents an ongoing challenge in variable-star research. Aims. We propose a new explanation. It is based on the observation that Blazhko stars seem to be located in the region of the instability strip where fundamental and first overtone modes are excited at the same time.Methods. An analysis of nonlinear and nonadiabatic pulsation models of RR Lyrae stars shows that a specific shock (called first overtone shock) may be generated by the perturbation of the fundamental mode by the transient first overtone. Results. The first overtone shock induces a sharp slowdown of the atmospheric layers during their infalling motion. This slowdown in turn affects the compression rate on the deep photospheric layers and the intensity of the κ-mechanism. After an amplification phase, the intensity of the main shock wave before the Blazhko maximum becomes high enough to provoke large radiative losses. These can be at least equal to 70% of the total energy flux of the shock, which induces a small decrease of the effective temperature at each pulsation cycle. In these conditions, when the intensity of the main shock reaches its highest critical value at the Blazhko maximum, it completely desynchronizes the motion of the phostospheric layers. At this point, the atmosphere relaxes and reaches a new synchronous state that occurs at the Blazhko minimum. Conclusions. The combined effects of these two shocks on the atmosphere cause the Blazhko effect. This effect can only exist if the first overtone mode is excited together with the fundamental mode. Because the involved physical mechanisms are essentially nonlinear (shocks, atmospheric dynamics, radiative losses, mode excitations), the Blazhko process is expected to be unstable and irregular. Consequently, the Blazhko process has a specific random nature that is in contrast with the pulsation of non-Blazhko stars.

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“…Ultra-precise data provided by these space telescopes allowed findings of, say, cycle-to-cycle variations now known as period doubling Kolenberg et al 2010;Benkő et al 2010) or longterm changes in the Blazhko effect and excitation of additional modes (Poretti et al 2010;Chadid et al 2010;Guggenberger et al 2012).…”

Section: Introductionmentioning

confidence: 99%

Bright Blazhko RRab Lyrae stars observed by ASAS and the SuperWASP surveys

Skarka

2014

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Aims. Period study of 321 fundamental mode RR Lyrae type stars (RRab), which had appropriate data in ASAS and SuperWASP surveys, was performed to complement and extend the list of known Blazhko stars in galactic field with bright stars up to 12.5 mag in maximum light.Methods. An individual approach was applied to each studied star. Permanent visual supervision was maintained to each procedure in data analysis (data cleaning, frequency spectra examination) to avoid missing any possible sign of the Blazhko effect. Period analysis was performed using Period04 software. Results. We found 100 stars to be definitely modulated. In 25 cases, previously unknown modulation was revealed and 8 new candidates for Blazhko stars were identified. Their modulation needs to be confirmed. In 18 previously found Blazhko stars, no modulation was detectable. Multiple modulation was revealed for eight stars that were previously proposed to show simple modulation. In total, there were twelve stars with some peculiarity in their modulation in the sample. This brings the incidence rate of multiple/irregularlymodulated stars to 12%. The ratio of the modulation periods of five of the double-modulated stars was within the ratios of small integers. One of stars studied, IK Hya, showed a very interesting frequency spectrum, which we interpret as changing Blazhko period between 71.81 and 75.57 days and an additional 1403-day-long cycle analogous to a four-year cycle of the prototype RR Lyr. The limits of the shorter period produce a beating period that is approximately twice as big as a 1403-day period. The newly revealed Blazhko star RZ CVn seems to undergo changes in the amplitude of the modulation, as well as in the basic pulsation and Blazhko periods. We found that the incidence rate of the Blazhko RR Lyraes is at least 31%, more likely even higher. It was also found that the majority of the Blazhko variables show triplet structures in their frequency spectra and that in 89% of these cases, the peak with larger amplitude is on the right-hand side of the main pulsation component.

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CoRoT light curves of RR Lyrae stars

Cited by 48 publications

References 37 publications

New results in RR Lyrae modeling: Convective cycles, additional modes and more

New results in RR Lyrae modeling: Convective cycles, additional modes and more

Atmospheric dynamics in RR Lyrae stars

Bright Blazhko RRab Lyrae stars observed by ASAS and the SuperWASP surveys

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