Blazhko effect in Cepheids and RR Lyrae stars

Szabo, Robert M.

doi:10.1017/s1743921313014397

Cited by 4 publications

(5 citation statements)

References 36 publications

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“…There are many more interesting features of the BL effect. Extensive reviews of the BL effect are provided in recent overviews by Szabó (2014), Kovács (2016), and Smolec (2016).…”

Section: Introductionmentioning

confidence: 99%

The SERMON project: 48 new field Blazhko stars and an investigation of modulation-period distribution

Skarka

Liška

Auer³

et al. 2016

A&A

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Aims. We investigated 1234 fundamental mode RR Lyrae stars observed by the All Sky Automated Survey (ASAS) to identify the Blazhko (BL) effect. A sample of 1547 BL stars from the literature was collected to compare the modulation-period distribution with stars newly identified in our sample. Methods. A classical frequency spectra analysis was performed using Period04 software. Data points from each star from the ASAS database were analysed individually to avoid confusion with artificial peaks and aliases. Statistical methods were used in the investigation of the modulation-period distribution. Results. Altogether we identified 87 BL stars (48 new detections), 7 candidate stars, and 22 stars showing long-term period variations. The distribution of modulation periods of newly identified BL stars corresponds well to the distribution of modulation periods of stars located in the Galactic field, Galactic bulge, Large Magellanic Cloud, and globular cluster M5 collected from the literature. As a very important by-product of this comparison, we found that pulsation periods of BL stars follow Gaussian distribution with the mean period of 0.54 ± 0.07 d, while the modulation periods show log-normal distribution with centre at log(P m [d]) = 1.78 ± 0.30 dex. This means that 99.7% of all known modulated stars have BL periods between 7.6 and 478 days. We discuss the identification of long modulation periods and show, that a significant percentage of stars showing long-term period variations could be classified as BL stars.

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“…There are many more interesting features of the BL effect. Extensive reviews of the BL effect are provided in recent overviews by Szabó (2014), Kovács (2016), and Smolec (2016).…”

Section: Introductionmentioning

confidence: 99%

The SERMON project: 48 new field Blazhko stars and an investigation of modulation-period distribution

Skarka

Liška

Auer³

et al. 2016

A&A

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“…Among many models proposed to explain the phenomenon, the model of Buchler & Kolláth [12], in which modulation is caused by the half-integer resonance between the radial modes (9:2 resonance between the fundamental mode and the ninth overtone, P F /P 9O = 9 : 2) is the most promising one. It is supported by the analysis of amplitude equations and recent Kepler observations (see [11]), but lacks confirmation from hydrodynamic modelling.…”

Section: Search For the Blazhko-type Modulationmentioning

confidence: 95%

“…The Blazhko effect is a quasi-periodic modulation of pulsation amplitude and phase which affects nearly 50% of stars pulsating in the fundamental mode (for a review see [11]). Despite being discovered more than 100 years ago, its physical origin remains unclear.…”

Section: Search For the Blazhko-type Modulationmentioning

confidence: 99%

Survey of hydrodynamic RR Lyrae models

Smolec

2015

EPJ Web of Conferences

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Abstract. We present a grid of hydrodynamic RR Lyrae-type models covering a large range of physical parameters. These models were computed with the aim to analyse the mode selection in these stars and to search for the Blazhko-type modulation. Initial results of the survey are reported. The data base of hydrodynamic RR Lyrae modelsAll models were computed with the Warsaw non-linear, convective pulsation codes [1]. Radiation is treated in the diffusion approximation and turbulent convection is treated with the model of Kuhfuß [2]. Each of the Lagrangian models comprise 150 mass shells extending down to 2 × 10 6 K. In the non-linear computations, each pulsation cycle is covered by at least 600 time-steps. All models adopt OPAL opacities [3] and Asplund et al.[4] solar mixture. Colors are computed using Kurucz [5] model atmospheres. The basic grid of physical parameters for non-linear models is presented in Tab. 1. Linear stability analysis is conducted in a much wider parameter range. Several sets of convective parameters that enter the turbulent convection model are considered. The full grid of models, with more than 10 000 light curves, will be published as an on-line database in 2015.

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“…The Y (RRblz) has a Blazhko effect that is a long-period modulation or a variation in period and amplitude of RR Lyrae stars (e.g. Szabó 2014). On the other hand, the Y (Rot) displays amplitude variation due the to the magnetic activity cycles and period variation due to differential rotation (e.g.…”

Section: Testing Frequency Uncertainitiesmentioning

confidence: 99%

New Insights into Time Series Analysis III: Setting constraints on period analysis

Lopes

Cross

Jablonski

2018

Monthly Notices of the Royal Astronomical Society

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E-science of photometric data requires automatic procedures and a precise recognition of periodic patterns to perform science as well as possible on large data. Analytical equations that enable us to set the best constraints to properly reduce processing time and hence optimize signal searches play a crucial role in this matter. These are increasingly important because the production of unbiased samples from variability indices and statistical parameters has not been achievable so far. We discuss the constraints used in periodic signals detection methods as well as the uncertainties in the estimation of periods and amplitudes. The frequency resolution necessary to investigate a time series is assessed with a new approach that estimates the necessary sampling resolution from shifts on the phase diagrams for successive frequency grid points.We demonstrate the underlying meaning of the oversampling factor. We reassess the frequency resolutions required to find the variability periods of EA stars and use the new resolutions to analyse a small sample of EA up Catalina stars, i.e. EA stars previously classified as having insufficient number of observations at the eclipses. As a result, the variability periods of four EA up stars were determined. Moreover, we have a new approach to estimate the amplitude and period variations. From these estimations information about the intrinsic variations of the sources are obtained. For a complete characterization of the light curve signal the period uncertainty and period variation must be determined. Constraints on periodic signal searches were analysed and delimited.

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Blazhko effect in Cepheids and RR Lyrae stars

Cited by 4 publications

References 36 publications

The SERMON project: 48 new field Blazhko stars and an investigation of modulation-period distribution

The SERMON project: 48 new field Blazhko stars and an investigation of modulation-period distribution

Survey of hydrodynamic RR Lyrae models

New Insights into Time Series Analysis III: Setting constraints on period analysis

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