Related papers: The frequency spectrum of periodically modulated s…
We examined the complete short cadence sample of Kepler RR Lyrae stars to further investigate the recently discovered dynamical effects such as period doubling and additional modes. Here we present the findings on four stars. V450 Lyr may…
A recently developed wavelet based approach is employed to characterize the scaling behavior of spectral fluctuations of random matrix ensembles, as well as complex atomic systems. Our study clearly reveals anti-persistent behavior and…
This article reports some preliminary results on an analysis of line bisectors of metal absorption lines of RR Lyrae, the prototype of its class of pulsators. The extensive data set used for this study consists of a time series of spectra…
We used the GEOS database to study the Blazhko effect of galactic RRab stars. The database is continuously enriched by maxima supplied by amateur astronomers and by a dedicated survey by means of the two TAROT robotic telescopes. The same…
The changes in brightness of an astronomical source as a function of time are key probes into that source's physics. Periodic and quasi-periodic signals are indicators of fundamental time (and length) scales in the system, while stochastic…
We present a detailed light curve analysis of RR Lyrae variables at multiple wavelengths using Fourier decomposition method. The time-series data for RR Lyrae variables in the Galactic bulge and the Magellanic Clouds are taken from the…
By using the full span of multicolor data on a representative sample of first overtone RR Lyrae stars in the Large Magellanic Cloud (LMC) we revisit the problem of the incidence rate of the amplitude/phase-modulated (Blazhko) stars.…
As shown by Mennickent, et al(2003), a subset of the blue variable stars in the Large Magellanic Cloud exhibit brightness variability of small amplitude in the period range 2.4 to 16 days as well as larger amplitude variability with periods…
This paper addresses the problem of expressing a signal as a sum of frequency components (sinusoids) wherein each sinusoid may exhibit abrupt changes in its amplitude and/or phase. The Fourier transform of a narrow-band signal, with a…
We present a highly simplified nonlinear hydrodynamical model to emulate the main observed features of amplitude modulation (commonly known as Blazhko effect) in RR Lyrae stars. The model is based on the assumption that the periodic flow…
We briefly discuss three cases of RR~Lyrae variable stars with Blazhko modulation from the OGLE Galactic bulge collection. In one of the discussed stars modulation with two periods is detected, in other star, we detect three Blazhko…
We present our analysis of photometric data in the Johnson B and V filter of the southern Blazhko star SS For. In parallel, we analyzed the V observations obtained with the ASAS-3 photometry of the star gathered between 2000 and 2008. In…
We present our analysis of Kepler observations of 29 RR Lyrae stars, based on 138-d of observation. We report precise pulsation periods for all stars. Nine of these stars had incorrect or unknown periods in the literature. Fourteen of the…
The knowledge of accurate stellar parameters is a keystone in several fields of stellar astrophysics, such as asteroseismology and stellar evolution. Although the fundamental parameters can be derived both from spectroscopy and multicolour…
We present analysis of the RR Lyrae star, LS Her and confirm the previously reported modulation to its Blazhko cycles. We performed Fourier analysis on two sectors (Sector 24 & 25) of data from the Transiting Exoplanet Survey Satellite…
We present a detailed nonlinear dynamical investigation of the Blazhko modulation of the Kepler RR Lyrae star V783 Cyg (KIC 5559631). We used different techniques to produce modulation curves, including the determination of amplitude…
The correlation of particular Fourier components of the light curves of RR Lyrae variables with metallicity, discovered by Simon and later by Kovacs and his coworkers, is shown to have the same explanation as the period ratios (period…
The results of an observation campaign of V0784 Ophiuchi over a time span of two years have revealed a multi-periodic Blazhko effect. A Blazhko effect for V0784 Ophiuchi has not been reported previously. From the observed light curves, 60…
More than 1300 variables classified provisionally as first overtone RR Lyrae pulsators in the MACHO variable star database of the Large Magellanic Cloud (LMC) have been subjected to standard frequency analysis. Based on the remnant power in…
Period study of 321 fundamental mode galactic field RR Lyrae type stars (RRab), which had appropriate data in ASAS and SuperWASP surveys, brighter than 12.5 mag in maximum light was performed. We found 100 stars to be definitely modulated.…