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

Skarka, Marek; Liška, Jiří; Auer, Reinhold Friedrich; Prudil, Z.; Juráňová, Anna; Sódor, Á.

doi:10.1051/0004-6361/201628855

Cited by 13 publications

(20 citation statements)

References 46 publications

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“…Median and average values of the modulation periods are 59.6 days and 126 days, respectively. The median value is basically the same as what was found by Skarka et al (2016). The distribution of the logarithm of the Blazhko periods is not Gaussian as it is best apparent from the bottom panels of Fig.…”

Section: Modulation Periodssupporting

confidence: 81%

Blazhko effect in the Galactic bulge fundamental mode RR Lyrae stars – II. Modulation shapes, amplitudes, and periods

Skarka

Prudil

Jurcsik

2020

Monthly Notices of the Royal Astronomical Society

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The number of stars observed by the Optical Gravitational Lensing Experiment (OGLE) project in the Galactic bulge offers an invaluable chance to study RR Lyrae stars in a statistical manner. We used data of 3141 fundamental-mode RR Lyrae stars showing the Blazhko effect observed in OGLE-IV to investigate a possible connection between modulation amplitudes and periods, light curve and pulsation characteristics. We found that there is no simple monotonic correlation between any combination of two parameters concerning the Blazhko and pulsation amplitudes, periods and the shape of the light curves. There are only systematic limits. There is a bottom limit of the modulation period with respect to the pulsation period. We also found that the possible range of modulation amplitudes decreases with increasing pulsation period which could point towards that the Blazhko effect is suppressed in cooler, larger, more luminous and less metal abundant bulge RR Lyrae stars. Our investigation revealed that the distribution of the modulation periods can be described with two populations of stars with the mean modulation periods of 48 and 186 days. There is a certain region with a low density of the modulated stars, which we call the Blazhko valley, in the pulsation period-modulation period plane. Based on the similarity of the modulation envelopes, basically every star can be assigned to one of six morphological classes. Double modulation was found in 25 per cent of the studied stars. Only 6.3 per cent of modulated stars belongs to the Oosterhoff group II.

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Section: Modulation Periodssupporting

confidence: 81%

Blazhko effect in the Galactic bulge fundamental mode RR Lyrae stars – II. Modulation shapes, amplitudes, and periods

Skarka

Prudil

Jurcsik

2020

Monthly Notices of the Royal Astronomical Society

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“…(i) BL stars -stars with detectable side peak(s) within f0 ± 0.3 c/d, but no closer than 1.5/TS (Nagy & Kovács 2006;Skarka et al 2016). As a BL star we also considered stars that showed unambiguous secular amplitude variations with side peaks indicating modulation period longer than 2/3 TS.…”

Section: Searching For the Bl Effectmentioning

confidence: 99%

Blazhko effect in the Galactic bulge fundamental mode RR Lyrae stars – I. Incidence rate and differences between modulated and non-modulated stars

Prudil

Skarka

2017

Mon. Not. R. Astron. Soc.

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We present the first paper of a series focused on the Blazhko effect in RR Lyrae type stars pulsating in the fundamental mode, that are located in the Galactic bulge. A comprehensive overview about the incidence rate and light-curve characteristics of the Blazhko stars is given. We analysed 8 282 stars having the best quality data in the OGLE-IV survey, and found that at least 40.3 % of stars show modulation of their light curves. The number of Blazhko stars we identified is 3 341, which is the largest sample ever studied implying the most relevant statistical results currently available. Using combined data sets with OGLE-III observations, we found that 50 % of stars that show unresolved close peaks to the main component in OGLE-IV are actually Blazhko stars with extremely long periods. Blazhko stars with modulation occur preferentially among RR Lyrae stars with shorter pulsation periods in the Galactic bulge. Fourier amplitude and phase coefficients based on the mean light curves appear to be substantially lower for Blazhko stars than for stars with unmodulated light curve in average. We derived new relations for the compatibility parameter D m in I passband and relations that allow for differentiating modulated and non-modulated stars easily on the basis of R 31 , φ 21 and φ 31 . Photometric metallicities, intrinsic colours and absolute magnitudes computed using empirical relations are the same for Blazhko and non-modulated stars in the Galactic bulge suggesting no correlation between the occurrence of the Blazhko effect and these parameters.

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“…1. The mean value of the Blazhko periods in M3 is larger than obtained for the inhomogeneous sample of stars by Skarka et al (2016) as can be seen in Fig. 1.…”

Section: Modulation Periodsmentioning

confidence: 61%

“…Collecting a large sample of Blazhko stars (1628 stars) Skarka et al (2016) found that the distribution of the modulation periods is log-normal with log(P mod ) = 1.78(3)±0.30 mean value. The 1σ uncertainty of the mean is given in parenthesis.…”

Section: Modulation Periodsmentioning

confidence: 99%

Blazhko type fundamental-mode RR Lyrae stars in the globular cluster, M3

Jurcsik

2019

Preprint

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Blazhko stars from the extended BV I C time series of RRab stars in the globular cluster, M3, are analysed. This is the largest sample of Blazhko stars with full details of their Blazhko properties in a homogeneous stellar system. Blazhko periods and lightcurve solutions are determined/estimated for 83 fundamental-mode variables. The lack of phase modulation in Oosterhoff-type II stars and the diminishing relative strength of the modulation in long-period Oosterhoff-type I stars are the regular tendencies found between the pulsation and modulation properties of Blazko stars. Similarly to previous results, no modulation of the longest-period stars is detected. The onset of the modulation in a previously regular RRab star, and the similar distribution of modulated and non-modulated stars imply that the modulation is a temporal property of RRL stars, which may occur at any time in any RRab star except the coolest ones. Comparing the modulation periods in M3 and in other samples of Blazhko stars, the mean log(P mod ) value is found to depend on the metallicity of the system. The separation of the temperature-and radius-change induced variations supports our previous finding that the photometric radius variation does not show any modulation. The pulsation-averaged mean brightness and temperature of Blazhko stars are found to be larger in the large-amplitude phase of the modulation than in the small-amplitude phase. The larger the amplitude of the modulation, the larger changes of the mean parameters are detected.

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

Cited by 13 publications

References 46 publications

Blazhko effect in the Galactic bulge fundamental mode RR Lyrae stars – II. Modulation shapes, amplitudes, and periods

Blazhko effect in the Galactic bulge fundamental mode RR Lyrae stars – II. Modulation shapes, amplitudes, and periods

Blazhko effect in the Galactic bulge fundamental mode RR Lyrae stars – I. Incidence rate and differences between modulated and non-modulated stars

Blazhko type fundamental-mode RR Lyrae stars in the globular cluster, M3

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