J. M. Benkő
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View article: Connections between the cycle-to-cycle light curve and O−C variations of non-Blazhko RR Lyrae stars
Connections between the cycle-to-cycle light curve and O−C variations of non-Blazhko RR Lyrae stars Open
Context. It is widely known that if the durations of the consecutive cycles of a pulsating star vary in a random fashion, the O−C diagram could show quasi-periodic or irregular variations, even when the actual average period is constant. I…
View article: Study of the Blazhko Type RRc stars in the Stripe 82 Region Using SDSS and ZTF
Study of the Blazhko Type RRc stars in the Stripe 82 Region Using SDSS and ZTF Open
RR Lyrae stars (RRLs) are pulsating stars, many of which also show a long-term variation called the Blazhko effect which is a modulation of amplitude and phase of the lightcurve. In this work, we searched for the incidence rate of the Blaz…
View article: Similar additional frequency patterns on fundamental- and overtone-mode RR Lyrae stars showing <i>f</i><sub>68</sub> frequencies
Similar additional frequency patterns on fundamental- and overtone-mode RR Lyrae stars showing <i>f</i><sub>68</sub> frequencies Open
Context. Until now, it has been accepted that the additional frequencies in the fundamental-(RRab) and overtone-mode pulsating (RRc and RRd) RR Lyrae stars are of a different nature. RRab stars show frequencies associated with periodic dou…
View article: Similar additional frequency patterns on fundamental and overtone mode RR Lyrae stars showing $f_{68}$ frequencies
Similar additional frequency patterns on fundamental and overtone mode RR Lyrae stars showing $f_{68}$ frequencies Open
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…
View article: Study of the Blazhko type RRc stars in the Stripe 82 region using SDSS and ZTF
Study of the Blazhko type RRc stars in the Stripe 82 region using SDSS and ZTF Open
RR Lyrae stars are pulsating stars, many of which also show a long-term variation called the Blazhko effect which is a modulation of amplitude and phase of the lightcurve. In this work, we searched for the incidence rate of the Blazhko eff…
View article: Frequency analysis of the first-overtone RR Lyrae stars based on Extended Aperture Photometry from K2 data
Frequency analysis of the first-overtone RR Lyrae stars based on Extended Aperture Photometry from K2 data Open
Context. Additional low-amplitude signals have been observed in many RR Lyrae stars separate from pulsations in radial modes. The most common of these are short-period signals forming a period ratio of around 0.60–0.65 with the first overt…
View article: Frequency analysis of the first-overtone RR Lyrae stars based on the Extended Aperture Photometry from the K2 data
Frequency analysis of the first-overtone RR Lyrae stars based on the Extended Aperture Photometry from the K2 data Open
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 …
View article: Time series analysis of bright <i>TESS</i> RRc stars: additional modes, phase variations, and more
Time series analysis of bright <i>TESS</i> RRc stars: additional modes, phase variations, and more Open
Using two years of data from the TESS space telescope, we have investigated the time series of 633 overtone pulsating field RR Lyrae (RRc) stars. The majority of stars (82.8 per cent) contain additional frequencies beyond the main pulsatio…
View article: Time series analysis of bright TESS RRc stars: Additional modes, phase variations and more
Time series analysis of bright TESS RRc stars: Additional modes, phase variations and more Open
Using two years of data from the TESS space telescope, we have investigated the time series of 633 overtone pulsating field RR Lyrae (RRc) stars. The majority of stars (82.8 per cent) contain additional frequencies beyond the main pulsatio…
View article: First Results on RR Lyrae Stars with the TESS Space Telescope: Untangling the Connections between Mode Content, Colors, and Distances
First Results on RR Lyrae Stars with the TESS Space Telescope: Untangling the Connections between Mode Content, Colors, and Distances Open
The Transiting Exoplanet Survey Satellite (TESS) space telescope is collecting continuous, high-precision optical photometry of stars throughout the sky, including thousands of RR Lyrae stars. In this paper, we present results for an initi…
View article: A comprehensive look at RR Lyrae stars through high-precision photometry and astrometry
A comprehensive look at RR Lyrae stars through high-precision photometry and astrometry Open
The TESS and Gaia missions are both collecting data of exquisite quality for RR Lyrae-type pulsating stars. We combine light curve shape information from TESS with distances and brightnesses from Gaia to build a detailed classification sch…
View article: Photometric and spectroscopic investigations of the Galactic field RRc candidates V764 Mon and HY Com
Photometric and spectroscopic investigations of the Galactic field RRc candidates V764 Mon and HY Com Open
By analyzing photometric and spectroscopic time series in this paper, we show that the pulsator V764 Mon, assumed to be the brightest RR Lyrae star in the sky, is in fact a rapidly rotating delta Scuti star with an unusually long dominant …
View article: Spectroscopic and photometric time series of the bright RRc star T Sex
Spectroscopic and photometric time series of the bright RRc star T Sex Open
We present spectroscopic time series observations on one of the brightest northern RRc stars, namely T Sex. Additionally, we also analysed extended photometric data sets, particularly the recent observations of the TESS space telescope. Th…
View article: Revisiting the <i>Kepler</i> non-Blazhko RR Lyrae sample: cycle-to-cyle variations and additional modes
Revisiting the <i>Kepler</i> non-Blazhko RR Lyrae sample: cycle-to-cyle variations and additional modes Open
We analyzed the long and short cadence light curves of the Kepler non-Blazhko\nRRab stars. We prepared the Fourier spectra, the Fourier amplitude and phase\nvariation functions, time-frequency representation, the O-C diagrams and their\nFo…
View article: The Delta Scuti star 38 Eri from the ground and from space
The Delta Scuti star 38 Eri from the ground and from space Open
MESA inlists associated with The Delta Scuti star 38 Eri from the ground and from space
View article: The Delta Scuti star 38 Eri from the ground and from space
The Delta Scuti star 38 Eri from the ground and from space Open
MESA inlists associated with The Delta Scuti star 38 Eri from the ground and from space
View article: The Delta Scuti star 38 Eri from the ground and from space
The Delta Scuti star 38 Eri from the ground and from space Open
We present and discuss the pulsational characteristics of the Delta Scuti star 38 Eri from photometric data obtained at two widely spaced epochs, partly from the ground (1998) and partly from space (MOST, 2011). We found 18 frequencies res…
View article: On the connection between almost periodic functions and Blazhko light curves
On the connection between almost periodic functions and Blazhko light curves Open
In this paper it is shown that the mathematical form which most precisely\ndescribes the Blazhko RR Lyrae light curves is connected to almost periodic\nfunctions and not to the mathematics of modulation. That is, the Blazhko effect\nis mor…
View article: A search for tight hierarchical triple systems amongst the eclipsing binaries in the CoRoT fields
A search for tight hierarchical triple systems amongst the eclipsing binaries in the CoRoT fields Open
We report a comprehensive search for hierarchical triple stellar system candidates amongst eclipsing binaries (EB) observed by the CoRoT spacecraft. We calculate and check eclipse timing variation (ETV) diagrams for almost 1500 EBs in an a…
View article: Multi-site, multi-colour and space photometry of a southern <i>δ</i> Scuti star, 38 Eri
Multi-site, multi-colour and space photometry of a southern <i>δ</i> Scuti star, 38 Eri Open
38 Eri is a δ Scuti star in the shell hydrogen burning stage of evolution, with a 0.04 mag peak-to-peak amplitude and a very complex light variation. It was discovered in 1971. In the subsequent investigation the star always showed a diffe…
View article: The<i>Kepler</i>Cepheid V1154 Cyg revisited: light curve modulation and detection of granulation
The<i>Kepler</i>Cepheid V1154 Cyg revisited: light curve modulation and detection of granulation Open
We present a detailed analysis of the bright Cepheid-type variable star V1154\nCygni using 4 years of continuous observations by the Kepler space telescope.\nWe detected 28 frequencies using standard Fourier transform method.We\nidentified…
View article: Finest light-curve details, physical parameters and period fluctuations of<i>CoRoT</i>RR Lyrae stars
Finest light-curve details, physical parameters and period fluctuations of<i>CoRoT</i>RR Lyrae stars Open
The CoRoT satellite supplied the scientific community with a huge data base of variable stars. Among them the RR Lyrae stars have intensively been discussed in numerous papers in the last few years, but the latest runs have not been checke…
View article: How to separate the low amplitude delta Scuti variation from the instrumental ones in CoRoT data?
How to separate the low amplitude delta Scuti variation from the instrumental ones in CoRoT data? Open
Rich regular frequency patterns were found in the Fourier spectra of low-amplitude delta Scuti stars observed by CoRoT satellite (see Paparó et al. 2016a,b). The CoRoT observations are, however, influenced by the disturbing effect of the S…
View article: <i>CoRoT</i>space photometry of seven Cepheids
<i>CoRoT</i>space photometry of seven Cepheids Open
A few Galactic classical Cepheids were observed in the programmes of space missions as Coriolis, MOST, and Kepler. An appealing opportunity was to detect additional non-radial modes, thus opening the possibility to perform asteroseismic st…
View article: Connection between the period and the amplitude of the Blazhko effect
Connection between the period and the amplitude of the Blazhko effect Open
\nWe found a possible relationship between the modulation period and the amplitude of the Blazhko RR Lyrae stars: long modulation period generally implies high modulation amplitude while the short modulation period results in small amplitu…
View article: The early phases of the Type Iax supernova SN 2011ay
The early phases of the Type Iax supernova SN 2011ay Open
We present a detailed study of the early phases of the peculiar supernova (SN) 2011ay based on BVRI photometry obtained at Konkoly Observatory, Hungary, and optical spectra taken with the Hobby–Eberly Telescope at McDonald Observatory, Tex…
View article: How to separate the low amplitude δ Scuti variation from the instrumental ones in CoRoT data?
How to separate the low amplitude δ Scuti variation from the instrumental ones in CoRoT data? Open
Rich regular frequency patterns were found in the Fourier spectra of low-amplitude δ Scuti stars observed by CoRoT satellite (see Paparó et al. in prep.). The CoRoT observations are, however, influenced by the disturbing effect of the Sout…
View article: Kepler photometry of RRc stars: peculiar double-mode pulsations and period doubling
Kepler photometry of RRc stars: peculiar double-mode pulsations and period doubling Open
We present the analysis of four first overtone RR Lyrae stars observed with the Kepler space telescope, based on data obtained over nearly 2.5 yr. All four stars are found to be multiperiodic. The strongest secondary mode with frequency f2…
View article: Dynamical investigation of modulated<i>Kepler</i>RR Lyrae stars
Dynamical investigation of modulated<i>Kepler</i>RR Lyrae stars Open
We performed a non-linear dynamical analysis on the Blazhko modulation for the first time. Our results suggest that the detection of chaotic nature behind the phenomenon is limited by the instrumental effects and the data processing proble…