The Kepler Characterization Of The Variability Among A- And F-Type Stars I. General Overview

dc.contributor.utaustinauthorBreger, Men_US
dc.creatorUytterhoeven, K.en_US
dc.creatorMoya, A.en_US
dc.creatorGrigahcene, A.en_US
dc.creatorGuzik, J. A.en_US
dc.creatorGutierrez-Soto, J.en_US
dc.creatorSmalley, B.en_US
dc.creatorHandler, G.en_US
dc.creatorBalona, L. A.en_US
dc.creatorNiemczura, E.en_US
dc.creatorMachado, L. F.en_US
dc.creatorBenatti, S.en_US
dc.creatorChapellier, E.en_US
dc.creatorTkachenko, A.en_US
dc.creatorSzabo, R.en_US
dc.creatorSuarez, J. C.en_US
dc.creatorRipepi, V.en_US
dc.creatorPascual, J.en_US
dc.creatorMathias, P.en_US
dc.creatorMartin-Ruiz, S.en_US
dc.creatorLehmann, H.en_US
dc.creatorJackiewicz, J.en_US
dc.creatorHekker, S.en_US
dc.creatorGruberbauer, M.en_US
dc.creatorGarcia, R. A.en_US
dc.creatorDumusque, X.en_US
dc.creatorDiaz-Fraile, D.en_US
dc.creatorBradley, P.en_US
dc.creatorAntoci, V.en_US
dc.creatorRoth, M.en_US
dc.creatorLeroy, B.en_US
dc.creatorMurphy, S. J.en_US
dc.creatorDe Cat, P.en_US
dc.creatorCuypers, J.en_US
dc.creatorKjeldsen, H.en_US
dc.creatorChristensen-Dalsgaard, J.en_US
dc.creatorBreger, M.en_US
dc.creatorPigulski, A.en_US
dc.creatorKiss, L. L.en_US
dc.creatorStill, M.en_US
dc.creatorThompson, S. E.en_US
dc.creatorVan Cleve, J.en_US
dc.description.abstractContext. 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 gamma Doradus (gamma Dor), delta Scuti (delta 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: gamma Dor, delta 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 gamma Dor and delta Sct range, also between 5 and 10 d(-1), which is a challenge for the current models. We find indications for the existence of delta Sct and gamma Dor stars beyond the edges of the current observational instability strips. The hybrid stars occupy the entire region within the delta Sct and gamma Dor instability strips and beyond. Non-variable stars seem to exist within the instability strips. The location of gamma Dor and delta 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 gamma Dor and delta Sct stars. Conclusions. Our results suggest a revision of the current observational instability strips of delta Sct and gamma Dor stars and imply an investigation of pulsation mechanisms to supplement the kappa mechanism and convective blocking effect to drive hybrid pulsations. Accurate physical parameters for all stars are needed to confirm these findings.en_US
dc.description.sponsorshipNASA's Science Mission Directorateen_US
dc.description.sponsorshipDeutsche Forschungsgemeinschaft (DFG) UY 52/1-1en_US
dc.description.sponsorshipSpanish National Plan of RD AYA2010-17803en_US
dc.description.sponsorshipAstroMadrid CAM S2009/ESP-1496en_US
dc.description.sponsorshipMNiSW NN 203 405139, NN 203 302635en_US
dc.description.sponsorshipAustrian Fonds zur Forderung der wissenschaftlichen Forschung P20526-N16en_US
dc.description.sponsorshipUNAM PAPIIT IN114309en_US
dc.description.sponsorshipHungarian Academy of Sciencesen_US
dc.description.sponsorshipHungarian OTKA K83790, MB08C 81013en_US
dc.description.sponsorshipNetherlands Organisation for Scientific Research (NWO)en_US
dc.description.sponsorshipSpanish SP2007-65475-C02-02, AYA 2010-21161-C02-02, CSD2006-00070en_US
dc.description.sponsorshipEuropean Community 269194en_US
dc.identifier.citationUytterhoeven, K., A. Moya, A. Grigahcène, J. A. Guzik, J. Gutiérrez-Soto, B. Smalley, G. Handler et al. >The Kepler characterization of the variability among A-and F-type stars-I. General overview.> Astronomy & Astrophysics, Vol. 534 (Oct., 2011): A125.en_US
dc.relation.ispartofserialAstronomy & Astrophysicsen_US
dc.rightsAdministrative deposit of works to Texas ScholarWorks: This works author(s) is or was a University faculty member, student or staff member; this article is already available through open access or the publisher allows a PDF version of the article to be freely posted online. The library makes the deposit as a matter of fair use (for scholarly, educational, and research purposes), and to preserve the work and further secure public access to the works of the University.en_US
dc.subjectstars: oscillationsen_US
dc.subjectstars: fundamental parametersen_US
dc.subjectbinaries: generalen_US
dc.subjectstars: variables: delta scutien_US
dc.subjectstars: statisticsen_US
dc.subjectgamma-doradus starsen_US
dc.subjectdelta-scuti starsen_US
dc.subjecthigh-resolution spectroscopyen_US
dc.subjecttime-series analysisen_US
dc.subjectmain-sequence starsen_US
dc.subjectrr lyrae starsen_US
dc.subjectspectral classificationen_US
dc.subjectfundamental parametersen_US
dc.subjectasteroseismic targetsen_US
dc.subjectastronomy & astrophysicsen_US
dc.titleThe Kepler Characterization Of The Variability Among A- And F-Type Stars I. General Overviewen_US

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