Cepheid investigations using the Kepler space telescope

Szabo, Robert M.; Szabados, László; Ngeow, Chow-Choong; Smolec, R.; Derekas, A.; Moskalik, P.; Nuspl, J.; Lehmann, H.; Fürész, Gábor; Molenda-Żakowicz, J.; Bryson, Stephen T.; Henden, A. A.; Kurtz, D. W.; Stello, Dennis; Nemec, J. M.; Benkő, J. M.; Бердников, Л. Н.; Bruntt, H.; Evans, Nancy Remage; Gorynya, N. A.; Pastukhova, E. N.; Simcoe, R.; Grindlay, J. E.; Los, E.; Doane, A.; Laycock, S.; Mink, Jessica; Champine, George A.; Sliski, A.; Handler, G.; Kiss, L. L.; Kollath, Zoltán; Kovács, József; Christensen‐Dalsgaard, J.; Kjeldsen, H.; Allen, Christopher S.; Thompson, Susan E.; Cleve, Jeffrey Van

doi:10.1111/j.1365-2966.2011.18342.x

Cited by 23 publications

(18 citation statements)

References 48 publications

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“…The first results based on the first four quarters of Kepler data were published by Szabó et al (2011) who found V1154 Cyg to be single periodic. The frequency analysis did not reveal any additional pulsation frequency while the period remained stable during the last 40 years.…”

Section: Introductionmentioning

confidence: 99%

TheKeplerCepheid V1154 Cyg revisited: light curve modulation and detection of granulation

Derekas

Plachy

Molnár

et al. 2016

Mon. Not. R. Astron. Soc.

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We present a detailed analysis of the bright Cepheid-type variable star V1154 Cygni using 4 years of continuous observations by the Kepler space telescope. We detected 28 frequencies using standard Fourier transform method. We identified modulation of the main pulsation frequency and its harmonics with a period of ∼159 d. This modulation is also present in the Fourier parameters of the light curve and the O-C diagram. We detected another modulation with a period of about 1160 d. The star also shows significant power in the low-frequency region that we identified as granulation noise. The effective timescale of the granulation agrees with the extrapolated scalings of red giant stars. Non-detection of solar-like oscillations indicates that the pulsation inhibits other oscillations. We obtained new radial velocity observations which are in a perfect agreement with previous years data, suggesting that there is no high mass star companion of V1154 Cygni. Finally, we discuss the possible origin of the detected frequency modulations.

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Section: Introductionmentioning

confidence: 99%

TheKeplerCepheid V1154 Cyg revisited: light curve modulation and detection of granulation

Derekas

Plachy

Molnár

et al. 2016

Mon. Not. R. Astron. Soc.

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“…The G star KIC 7548061 (V1154 Cyg) is a known and well-studied Cepheid (e.g. Pigulski et al 2009) and is the subject of a dedicated paper based on Kepler data by Szabó et al (2011). Sixty-two stars are known to belong to multiple systems, including at least fourteen eclipsing binaries (EB; KIC 1432149, Hartman et al 2004;KIC 10206340, Malkov et al 2006; catalogues by Prša et al 2011;.…”

Section: Sample Stars In the Literaturementioning

confidence: 99%

TheKeplercharacterization of the variability among A- and F-type stars

Uytterhoeven

Moya

Grigahcène

et al. 2011

A&A

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Context. The Kepler spacecraft is providing time series of photometric data with micromagnitude precision for hundreds of A-F type stars. Aims. We present a first general characterization of the pulsational behaviour of A-F type stars as observed in the Kepler light curves of a sample of 750 candidate A-F type stars, and observationally investigate the relation between γ Doradus (γ Dor), δ Scuti (δ Sct), and hybrid stars. Methods. We compile a database of physical parameters for the sample stars from the literature and new ground-based observations. We analyse the Kepler light curve of each star and extract the pulsational frequencies using different frequency analysis methods. We construct two new observables, "energy" and "efficiency", related to the driving energy of the pulsation mode and the convective efficiency of the outer convective zone, respectively. Results. We propose three main groups to describe the observed variety in pulsating A-F type stars: γ Dor, δ Sct, and hybrid stars. We assign 63% of our sample to one of the three groups, and identify the remaining part as rotationally modulated/active stars, binaries, stars of different spectral type, or stars that show no clear periodic variability. 23% of the stars (171 stars) are hybrid stars, which is a much higher fraction than what has been observed before. We characterize for the first time a large number of A-F type stars (475 stars) in terms of number of detected frequencies, frequency range, and typical pulsation amplitudes. The majority of hybrid stars show frequencies with all kinds of periodicities within the γ Dor and δ Sct range, also between 5 and 10 d −1 , which is a challenge for the current models. We find indications for the existence of δ Sct and γ Dor stars beyond the edges of the current observational instability strips. The hybrid stars occupy the entire region within the δ Sct and γ Dor instability strips and beyond. Non-variable stars seem to exist within the instability strips. The location of γ Dor and δ Sct classes in the (T eff , log g)-diagram has been extended. We investigate two newly constructed variables, "efficiency" and "energy", as a means to explore the relation between γ Dor and δ Sct stars. Conclusions. Our results suggest a revision of the current observational instability strips of δ Sct and γ Dor stars and imply an investigation of pulsation mechanisms to supplement the κ mechanism and convective blocking effect to drive hybrid pulsations. Accurate physical parameters for all stars are needed to confirm these findings.

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“…Photometry was obtained from the images using SEXTRACTOR (Bertin & Arnouts 1996), and calibrated to the standard magnitudes using standard star observation from Landolt (2009). Further details about the telescopes, the CCDs and the reduction of the imaging data can be found in Szabó et al (2011) andNgeow (2012), who used the same instrumentation for monitoring the Cepheid V1154 Cyg located within the Kepler field of view ).…”

Section: Ground-based Colour Photometrymentioning

confidence: 99%

The complex case of V445 Lyr observed with Kepler: two Blazhko modulations, a non-radial mode, possible triple mode RR Lyrae pulsation, and more

Guggenberger¹,

Kolenberg²,

Nemec³

et al. 2012

Monthly Notices of the Royal Astronomical Society

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Rapid and strong changes in the Blazhko modulation of RR Lyrae stars, as have recently been detected in high-precision satellite data, have become a crucial topic in finding an explanation of the long-standing mystery of the Blazhko effect. We present here an analysis of the most extreme case detected so far, the RRab star V445 Lyr (KIC 6186029) which was observed with the Kepler space mission. V445 Lyr shows very strong cycle-to-cycle changes in its Blazhko modulation, which are caused by both a secondary long-term modulation period and irregular variations. In addition to the complex Blazhko modulation, V445 Lyr also shows a rich spectrum of additional peaks in the frequency range between the fundamental pulsation and the first harmonic. Among those peaks, the second radial overtone could be identified, which, combined with a metallicity estimate of [Fe/H] = −2.0 dex from spectroscopy, allowed us to constrain the mass (0.55-0.65 M ) and luminosity (40-50 L ) of V445 Lyr through theoretical Petersen diagrams. A non-radial mode and possibly the first overtone are also excited. Furthermore, V445 Lyr shows signs of the period-doubling phenomenon and a longterm period change. A detailed Fourier analysis along with a study of the O − C variation of V445 Lyr is presented, and the origin of the additional peaks and possible causes of the changes in the Blazhko modulation are discussed. The results are then put into context with those of the only other star with a variable Blazhko effect for which a long enough set of high-precision continuous satellite data has been published so far, the CoRoT star 105288363.

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Cepheid investigations using the Kepler space telescope

Cited by 23 publications

References 48 publications

TheKeplerCepheid V1154 Cyg revisited: light curve modulation and detection of granulation

TheKeplerCepheid V1154 Cyg revisited: light curve modulation and detection of granulation

TheKeplercharacterization of the variability among A- and F-type stars

The complex case of V445 Lyr observed with Kepler: two Blazhko modulations, a non-radial mode, possible triple mode RR Lyrae pulsation, and more

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