J/AJ/166/83ivo://CDS.VizieR/J/AJ/166/83doi:10.26093/cds/vizier.51660083CDSLi L.-J.Qian S.-B.Shi X.-D.Zhu L.-Y.2024-11-06T20:19:06Z2024-03-26T07:54:26ZCDS support team

CDS, Observatoire de Strasbourg, 11 rue de l'Universite, F-67000 Strasbourg, France

cds-question@unistra.frvariable-starsvisible-astronomyphotometryNoting the weakest modulation and relatively high metal abundance of the Ab-type RR-Lyrae star V838Cyg, we collected the photometric data of this star from several sky surveys to carry out an in-depth analysis. The O-C diagram shows that the pulsation period of V838Cyg increases linearly over a long timescale. In a reanalysis of the high-precision Kepler data, we confirmed the modulation with a period of 59.45{+/-}0.07days found by Benko et al., and also found an additional weak modulation with a longer period (840{+/-}21 days). After a series of analyses, we incline to the view that the mechanisms causing the two modulations are different: the former is more similar to the typical Blazhko effect, while the mechanism leading to the latter may be an extrinsic factor. We also collected and compared the modulation and physical parameters of other Blazhko RRLyrae stars from several works in the literature, and find that there is a potential negative correlation between the modulation amplitude (or upper limit of amplitude) and the metal abundance. We infer that the relatively high metal abundance will promote convection in the outer stellar atmosphere, and then inhibit those factors (turbulence, shock wave, etc.) that may cause Blazhko modulation. Future observations and research work can be carried out with reference to this viewpoint. We also introduce the moire effects that appear in the Kepler long- cadence light curves and their possible interference in the previous analyses.2023AJ....166...83Lhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/AJ/166/83CatalogResearchIsServedByTAP VizieR generic servicerelated-toII/366 : ASAS-SN catalog of variable stars (Jayasinghe+, 2018-2020)I/358 : Gaia DR3 Part 4. Variability (Gaia Collaboration, 2022)J/AJ/108/1016 : Kinematics of local RR lyrae stars. I. (Layden, 1994)J/A+A/476/307 : Period variations in galactic RRab stars (Le Borgne+, 2007)J/other/IBVS/5889 : Minima and maxima of 380 variables (Hubscher+, 2009)J/other/IBVS/5941 : Minima and maxima of 292 variables (Hubscher+, 2010)J/other/IBVS/5984 : Minima and maxima of 503 variables (Hubscher, 2011)J/A+A/528/A90 : SuperWASP short period eclipsing binaries (Norton+, 2011)J/A+A/535/A3 : SuperWASP obs of pulsating Am stars (Smalley+, 2011)J/AJ/144/39 : Galactic RRab from GEOS RR Lyr Survey (Le Borgne+, 2012)J/ApJS/213/31 : Blazhko effect from 4yr of Kepler data (Benko+, 2014)J/ApJS/211/24 : Rotation periods of Kepler MS stars (McQuillan+, 2014)J/ApJ/788/48 : X-ray through NIR photometry of NGC 2617 (Shappee+, 2014)J/A+A/562/A90 : Times of maximum light of Blazhko RRab stars (Skarka, 2014)J/ApJ/809/L19 : LCs of RR Lyrae stars V350 Lyr & KIC 7021124 (Henry+, 2015)J/MNRAS/459/4360 : Field RR Lyrae stars (Liska+, 2016)J/MNRAS/466/2602 : Blazhko effect in Galactic RR Lyrae (Prudil+, 2017)J/MNRAS/494/1237 : Blazhko effect in Galactic RR Lyrae II (Skarka+, 2020)J/AJ/161/193 : BVRI light curve of RR Lyrae V* AX UMa (Li+, 2021)J/ApJ/912/144 : Metallicity of Gal. RR Lyrae from opt&IR LC (Mullen+, 2021)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/AJ/166/83https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/AJ/166/83http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/AJ/166/83https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/AJ/166/83https://vizier.iucaa.in/viz-bin/votable?-source=J/AJ/166/83http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/AJ/166/83GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapOpticaldefaultJ/AJ/166/83/table1V838 Cyg TESS light curverecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintBJD[1683/2769] Barycentric Julian Date; BJD-2457000dtime.epochdoubleindexedDFlux[-7.64/45.5] Change in fluxphot.flux;arith.ratiodoubleJ/AJ/166/83/fig2O-C, amplitude and Fourier coefficient modulationsrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintMax[132/1591] Time of light maximum; BJD-2454833dtime.epochdoubleOCmax1[-0.02/-0.008] Maximum O-C value (1)dstat.fit.residualdoubleOCmax2[-0.002/0.001] Maximum O-C residuals (2)dstat.fit.residualdoublee_Max[3e-5/0.0005] Uncertainty in Maxdstat.error;stat.maxdoubleMin[131/1591] Times of light minimum; BJD-2454833dtime.epochdoubleOCmin1[-0.08/-0.07] Minimum O-C value (1)dstat.fit.residualdoubleOCmin2[-0.002/0.002] Minimum O-C residuals (2)dstat.fit.residualdoublee_Min[0.0001/0.002] Uncertainty in Mindstat.error;stat.mindoubleAmp[1.08/1.14] Full amplitudemagsrc.var.amplitudefloate_Amp[0.0005/0.009] Uncertainty in Ampmagstat.errorfloatA1[0.38/0.41] Fourier A_1_ parametermagstat.fit.paramfloate_A1[0.0002/0.004] Uncertainty in A1magstat.errorfloatmaxmag[-0.78/-0.72] Magnitude at light maximummagphot.magfloate_maxmag[0.0003/0.006] Uncertainty in maxmagmagstat.error;phot.mag;stat.maxfloatR21[0.46/0.47] Fourier R_21_ parameterstat.fit.paramfloate_R21[0.0006/0.006] Uncertainty in R21stat.errorfloatR31[0.34/0.36] Fourier R_31_ parameterstat.fit.paramfloate_R31[0.0005/0.005] Uncertainty in R31stat.errorfloatphi21[2.29/2.32] Fourier {phi}_21_ parameterstat.fit.paramfloate_phi21[0.001/0.04] Uncertainty in phi21stat.errorfloatphi31[4.84/4.88] Fourier {phi}_31_ parameterstat.fit.paramfloate_phi31[0.002/0.05] Uncertainty in phi31stat.errorfloat