Related papers: A Double-Mode RR Lyrae Star with a Strong Fundamen…
Up to now, it seemed that the additional frequencies in the fundamental mode (RRab) and in the overtone mode pulsating (RRc and RRd) RR Lyrae stars have different nature. RRab stars show frequencies associated with periodic doubling, as…
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 presence of a magnetic field can have a strong impact on the evolution of a binary star. However, only a dozen of magnetic OB binaries are known as of today and available to study this effect, including very few magnetic pulsating…
Aim: The aim of this work was to search for double mode pulsators among RR Lyr variables of globular cluster Omega Cen. Methods: We conducted a systematic frequency analysis of CASE photometry of Omega Cen RR Lyr stars. We searched for…
RR Lyrae (RRL) variable stars are cornerstone distance indicators. In particular, double-mode RR Lyrae (RRd) stars enable period--luminosity relations (PLRs) that are less sensitive to metallicity, reducing systematic biases in distance…
The RR Lyrae instability strip (IS) in NGC 1851 is investigated, and a model is presented which reproduces the pulsational properties of the RR Lyrae population. In our model, a stellar component within the IS that displays minor helium…
We report evidence for a new class of variable star, which we dub millimagnitude RR Lyrae (mmRR). From K2 observations of the globular cluster M4, we find that out of 24 horizontal branch stars not previously known to be RR Lyrae variables,…
Strange modes can occur in radiative classical Cepheids and RR Lyrae models. These are vibrational modes that are trapped near the surface as a result of a 'potential barrier' caused by the sharp hydrogen partial ionization region.…
V473 Lyrae is the only Galactic Cepheid with confirmed periodic amplitude and phase variations similar to the Blazhko effect observed in RR Lyrae stars. We collected all available photometric data and some radial velocity measurements to…
NSV 14264 and NSV 14172 are suspected to be variable stars of RR Lyr type (Brun, 1964). They were observed during three nights in October 2018 with a 25cm diameter telescope. These observations completed by ASAS-SN survey data bring to the…
Space-based photometric telescopes stirred up stellar astrophysics in the last decade, and RR Lyrae stars have not been an exception from that either. The long, quasi-continuous, high-precision data from MOST, CoRoT and Kepler revealed a…
Additional low-amplitude signals are observed in many RR Lyrae stars, beside the pulsations in radial modes. The most common ones are short-period signals forming a period ratio of around 0.60--0.65 with the first overtone, or long-period…
Four stars pulsating simultaneously with a dominant period $P_D$$\in$(0.28,0.39) d and an {\it additional} period $P_A$$\in$(0.20,0.27) d have been identified from among the more than 3000 RR Lyrae stars observed by the Kepler space…
The line profile variability and photometric variability of the O9.5 Vp star HD93521 are examined in order to establish the properties of the non-radial pulsations in this star. Fourier techniques are used to characterize the modulations of…
We have analysed high-precision photometry of 77 double-mode RR Lyrae (RRd) stars observed by NASA's Kepler-K2 mission during Campaigns 1-18. Among those stars, we have identified several low-period ratio variables, belonging either to a…
We report the discovery of a new double-mode RR Lyrae variable (RRd) in the field of our Galaxy: CU Comae. CU Comae is the sixth such RRd identified to date and is the most metal-poor RRd ever detected. Based on BVI CCD photometry spanning…
We present new photometric observations of the $\beta$ Lyrae-type eclipsing binary systems NSVS 7322420 and NSVS 5726288. These observations represent the first multi-band photometry performed on these systems. The light curves were…
We describe a methodology that allows us to follow the pulsational behavior of an RR Lyrae model consistently and automatically along its evolutionary track throughout the whole instability strip. It is based on the powerful amplitude…
We discuss visual observations spanning nearly 70 years of the nearby semiregular variable R Doradus. Using wavelet analysis, we show that the star switches back and forth between two pulsation modes having periods of 332 days and about 175…
A new, extended time-series photometry of M3 RR Lyrae stars has revealed that four of the ten double-mode stars show large-amplitude Blazhko modulation of both radial modes. The first, detailed analysis of the peculiar behavior of the…