J/MNRAS/472/1618ivo://CDS.VizieR/J/MNRAS/472/1618doi:10.26093/cds/vizier.74721618CDSGiles H.A.C.Collier Cameron A.Haywood R.D.2024-08-17T20:20:44Z2020-08-11T09:52:22ZCDS support team

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

cds-question@unistra.frvariable-starsWide-field high-precision photometric surveys such as Kepler have produced reams of data suitable for investigating stellar magnetic activity of cooler stars. Starspot activity produces quasi-sinusoidal light curves whose phase and amplitude vary as active regions grow and decay over time. Here we investigate, first, whether there is a correlation between the size of starspots - assumed to be related to the amplitude of the sinusoid - and their decay time-scale and, secondly, whether any such correlation depends on the stellar effective temperature. To determine this, we computed the auto-correlation functions of the light curves of samples of stars from Kepler and fitted them with apodised periodic functions. The light-curve amplitudes, representing spot size, were measured from the root-mean-squared scatter of the normalized light curves. We used a Monte Carlo Markov Chain to measure the periods and decay time-scales of the light curves. The results show a correlation between the decay time of starspots and their inferred size. The decay time also depends strongly on the temperature of the star. Cooler stars have spots that last much longer, in particular for stars with longer rotational periods. This is consistent with current theories of diffusive mechanisms causing starspot decay. We also find that the Sun is not unusually quiet for its spectral type - stars with solar-type rotation periods and temperatures tend to have (comparatively) smaller starspots than stars with mid-G or later spectral types.2017MNRAS.472.1618Ghttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/MNRAS/472/1618CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toV/133 : Kepler Input Catalog (Kepler Mission Team, 2009)J/ApJS/211/24 : Rotation periods of Kepler MS stars (McQuillan+, 2014)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/MNRAS/472/1618https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/MNRAS/472/1618http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/MNRAS/472/1618https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/MNRAS/472/1618https://vizier.iucaa.in/viz-bin/votable?-source=J/MNRAS/472/1618http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/MNRAS/472/1618GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/MNRAS/472/1618/table (Full results)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/MNRAS/472/1618/table?https://vizier.iucaa.in/viz-bin/conesearch/J/MNRAS/472/1618/table?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/MNRAS/472/1618/table?GETtext/xml+votable180.050000true291.0336936.77104190.0055555555555555564/922-923 933-935 944-945 5/3645-3647 3683 3704 3706 3730-3731 3784-3785 3789 3792 6/14567 14573 14575 14577-14579 14730-14731 14744 14746 14749-14751 14792 14794-14795 14822 14828 14830 14914-14916 14918-14919 15040-15041 15043-15045 15057 15059-15062 15145-15149 15151 15153-15155 15160 15172-15174 15176 15178 15200 15232https://cdsarc.cds.unistra.fr/viz-bin/moc/J/MNRAS/472/1618?format=asciidefaultJ/MNRAS/472/1618/tableFull resultsrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintKICKIC numbermeta.id;meta.mainintPMCMCMCMC periodtime.periodfloate_PMCMCrms uncertainty on PMCMCstat.errorfloatPMCQ14MCQ14 periodtime.periodfloate_PMCQ14rms uncertainty on PMCQ14stat.errorfloattauResultant decay lifetimedtime.agefloate_taurms uncertainty on taudstat.errorfloatrmsRoot mean square scatter of individual Kepler light curves which were normalized to a mean flux of unitystat.stdevdoubleF8F8 parameterstat.fit.paramdoubleloggSurface gravitylog(cm.s**-2)phys.gravityfloatTeffEffective temperatureKphys.temperature.effectiveintPe1/Pe2Pe1/Pe2 ratiostat.fit.paramdoublePe2/Pe3Pe2/Pe3 ratiostat.fit.paramdouble_RAPositions from KIC (right ascension part)degpos.eq.ra;meta.main_DEPositions from KIC (declination part)degpos.eq.dec;meta.main