Blazhko RR Lyrae light curves as modulated signals

Monthly Notices of the Royal Astronomical Society (Impact Factor: 5.52). 06/2011; 417. DOI: 10.1111/j.1365-2966.2011.19313.x
Source: arXiv

ABSTRACT We present an analytical formalism for the description of Blazhko RR Lyrae
light curves in which employ a treatment for the amplitude and frequency
modulations in a manner similar to the theory of electronic signal
transmitting. We assume monoperiodic RR Lyrae light curves as carrier waves and
modulate their amplitude (AM), frequency (FM), phase (PM), and as a general
case we discuss simultaneous AM and FM. The main advantages of this handling
are the following: (i) The mathematical formalism naturally explains numerous
light curve characteristics found in Blazhko RR Lyrae stars such as mean
brightness variations, complicated envelope curves, non-sinusoidal frequency
variations. (ii) Our description also explains properties of the Fourier
spectra such as apparent higher-order multiplets, amplitude distribution of the
side peaks, the appearance of the modulation frequency itself and its
harmonics. In addition, comparing to the traditional method, our light curve
solutions reduce the number of necessary parameters. This formalism can be
applied to any type of modulated light curves, not just for Blazhko RR Lyrae

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    ABSTRACT: The correct amplitude and phase modulation formalism of the Blazhko modulation is given. The harmonic order dependent amplitude and phase modulation form is equivalent with the Fourier decomposition of multiplets. The amplitude and phase modulation formalism used in electronic transmission technique as introduced by Benk\H{o}, Szab\'o and Papar\'o (2011, MNRAS 417, 974) for Blazhko stars oversimplifies the amplitude and phase modulation functions thus it does not describe the light variation in full detail. The results of the different formalisms are compared and documented by fitting the light curve of a real Blazhko star, CM UMa.
    Monthly Notices of the Royal Astronomical Society 06/2012; 424(4). · 5.52 Impact Factor
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    ABSTRACT: We modelled the light curves of modulated multiperiodically pulsating stars by a simple double-mode pulsation with combined amplitude and frequency modulations. The synthetic light curves and their spectra show similar features to those we found and discussed for monoperiodic stars. Comparing the synthetic light curves and their spectra with the observed ones helps us to classify the modulations and to distinguish between long-period modulation (Blazhko effect) and the other types of amplitude and/or period changes.
    Proceedings of the International Astronomical Union 04/2012; 7(S285):286-288.
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    ABSTRACT: This study investigates periodic modulation of the light curve of the RRc star TV Boo and its physical parameters based on photometric data. This phenomenon, known as the Blazhko effect, is quite rare among RRc stars. The frequency analysis based on the data gathered at the Masaryk University Observatory (MUO) and also using SuperWASP data revealed symmetrically structured peaks around the main pulsation frequency and its harmonics, which indicate two modulation components of the Blazhko period. The main modulation periodicity was found to be 9.7374 ± 0.0054 d. This is one of the shortest known Blazhko periods among RRc stars. The second modulation period (21.5 ± 0.2 d) causes changes of the Blazhko effect itself. Some indices show that TV Boo could be affected by long-term changes of the order of years. Basic physical parameters were estimated via an MUO V light-curve solution using Fourier parameters. TV Boo seems to be a low-metallicity star with [Fe/H] = -1.89.
    Monthly Notices of the Royal Astronomical Society 01/2013; 428(2):1442-1448. · 5.52 Impact Factor

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