J/A+A/622/A85ivo://CDS.VizieR/J/A+A/622/A85doi:10.26093/cds/vizier.36220085CDSNielsen M.B.Gizon L.Cameron R.H.Miesch M.2019-02-01T12:33:56Z2019-01-31T09:55:25ZCDS support team

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

cds-question@unistra.frspace-observatoriesobservational-astronomymagnetic-fieldsDuring the solar magnetic activity cycle the emergence latitudes of sunspots change, leading to the well-known butterfly diagram. This phenomenon is poorly understood for other stars since starspot latitudes are generally unknown. The related changes in starspot rotation rates caused by latitudinal differential rotation can however be measured. Using the set of 3093 Kepler stars with activity cycles identified by Reinhold et al. (2017A&A...603A..52R, Cat. J/A+A/603/A52), we aim to study the temporal change in starspot rotation rates over magnetic activity cycles, and how this relates to the activity level, the mean rotation rate of the star, and its effective temperature. We measured the photometric variability as a proxy for the magnetic activity and the spot rotation rate in each quarter over the duration of the Kepler mission. We phase-fold these measurements with the cycle period. To reduce random errors we perform averages over stars with comparable mean rotation rates and effective temperature at fixed activity-cycle phases. We detect a clear correlation between the variation of activity level and the variation of the starspot rotation rate. The sign and amplitude of this correlation depends on the mean stellar rotation and -- to a lesser extent -- on the effective temperature. For slowly rotating stars (rotation periods between 15-28 days) the starspot rotation rates are clearly anti-correlated with the level of activity during the activity cycles. A transition is observed around rotation periods of 10-15 days, where stars with effective temperature above 4200K instead show positive correlation. Our measurements can be interpreted in terms of a stellar "butterfly diagram", but these appear different from the Sun's since the starspot rotation rates are either in phase or anti-phase with the activity level. Alternatively, the activity cycle periods observed by Kepler are short (around 2.5 years) and may therefore be secondary cycles, perhaps analogous to the solar quasi-biennial oscillations.2019A&A...622A..85Nhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/622/A85CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toV/133 : Kepler Input Catalog (Kepler Mission Team, 2009)J/ApJS/211/2 : Q1-16 Kepler targets revised stellar properties (Huber+, 2014)J/ApJS/211/24 : Rotation periods of Kepler MS stars (McQuillan+, 2014)J/A+A/603/A52 : Activity cycles in 3203 Kepler stars (Reinhold+, 2017)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/622/A85https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/622/A85http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/622/A85https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/622/A85https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/622/A85http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/622/A85GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/A+A/622/A85/cyclepar (Activity cycle parameters for 3093 stars)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/622/A85/cyclepar?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/622/A85/cyclepar?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/622/A85/cyclepar?GETtext/xml+votable180.050000true290.958203136.68662030.0055555555555555564/922-923 933-935 944-946 5/3645-3647 3683 3704 3706 3729-3731 3760 3788-3789 3792 6/14559 14567 14573 14575 14577-14579 14730-14731 14744 14746 14749-14751 14792 14794-14795 14822 14828 14830 14914-14915 15044-15045 15057 15059-15062 15160 15172-15174 15176 15178 15200 15232https://cdsarc.cds.unistra.fr/viz-bin/moc/J/A+A/622/A85?format=asciidefaultJ/A+A/622/A85/cycleparActivity cycle parameters for 3093 starsnu6? Rotation rate in Q6uHzphys.veloc.rotatfloatnullablerecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintKICKepler Input Catalog numbermeta.id;meta.mainintTeffEffective surface temperature from Huber et al. (2014ApJS..211....2H, Cat. J/ApJS/211/2), Table 4Kphys.temperature.effectiveintloggSurface gravity from Huber et al. (2014ApJS..211....2H, Cat. J/ApJS/211/2), Table 4log(cm.s**-2)phys.gravityfloatH14Display the Huber et al. (2014, Cat. J/ApJS/211/2) datameta.ref.urlcharPcycActivity cycle period from Reinhold et al. (2017A&A...603A..52R, Cat. J/A+A/603/A52)dtime.periodfloatphi0Time of zero phase from Reinhold et al. (2017A&A...603A..52R, Cat. J/A+A/603/A52)dtime.epochfloatnurotMean rotation rate from McQuillan et al. (2014ApJS..211...24M, Cat. J/ApJS/211/24) (1)uHzphys.veloc.rotatfloatM14Display the McQuillan et al. (2014, Cat. J/ApJS/211/24) datameta.ref.urlcharnu1? Rotation rate in Q1uHzphys.veloc.rotatfloatnullablenu2? Rotation rate in Q2uHzphys.veloc.rotatfloatnullablenu3? Rotation rate in Q3uHzphys.veloc.rotatfloatnullablenu4? Rotation rate in Q4uHzphys.veloc.rotatfloatnullablenu5? Rotation rate in Q5uHzphys.veloc.rotatfloatnullablenu7? Rotation rate in Q7uHzphys.veloc.rotatfloatnullablenu8? Rotation rate in Q8uHzphys.veloc.rotatfloatnullablenu9? Rotation rate in Q9uHzphys.veloc.rotatfloatnullablenu10? Rotation rate in Q10uHzphys.veloc.rotatfloatnullablenu11? Rotation rate in Q11uHzphys.veloc.rotatfloatnullablenu12? Rotation rate in Q12uHzphys.veloc.rotatfloatnullablenu13? Rotation rate in Q13uHzphys.veloc.rotatfloatnullablenu14? Rotation rate in Q14uHzphys.veloc.rotatfloatnullablenu15? Rotation rate in Q15uHzphys.veloc.rotatfloatnullablenu16? Rotation rate in Q16uHzphys.veloc.rotatfloatnullablenu17? Rotation rate in Q17uHzphys.veloc.rotatfloatnullableA1? Integral of power spectral density in Q1(10-6)+2stat.fit.paramdoublenullableA2? Integral of power spectral density in Q2(10-6)+2stat.fit.paramdoublenullableA3? Integral of power spectral density in Q3(10-6)+2stat.fit.paramdoublenullableA4? Integral of power spectral density in Q4(10-6)+2stat.fit.paramdoublenullableA5? Integral of power spectral density in Q5(10-6)+2stat.fit.paramdoublenullableA6? Integral of power spectral density in Q6(10-6)+2stat.fit.paramdoublenullableA7? Integral of power spectral density in Q7(10-6)+2stat.fit.paramdoublenullableA8? Integral of power spectral density in Q8(10-6)+2stat.fit.paramdoublenullableA9? Integral of power spectral density in Q9(10-6)+2stat.fit.paramdoublenullableA10? Integral of power spectral density in Q10(10-6)+2stat.fit.paramdoublenullableA11? Integral of power spectral density in Q11(10-6)+2stat.fit.paramdoublenullableA12? Integral of power spectral density in Q12(10-6)+2stat.fit.paramdoublenullableA13? Integral of power spectral density in Q13(10-6)+2stat.fit.paramdoublenullableA14? Integral of power spectral density in Q14(10-6)+2stat.fit.paramdoublenullableA15? Integral of power spectral density in Q15(10-6)+2stat.fit.paramdoublenullableA16? Integral of power spectral density in Q16(10-6)+2stat.fit.paramdoublenullableA17? Integral of power spectral density in Q17(10-6)+2stat.fit.paramdoublenullableSimbadSimbad column added by the CDSmeta.ref.urlchar_RARight Ascension (J2000) from SIMBAD (not part of the original data)degpos.eq.ra;meta.main_DEDeclination (J2000) from SIMBAD (not part of the original data)degpos.eq.dec;meta.main