J/ApJS/209/5ivo://CDS.VizieR/J/ApJS/209/5doi:10.26093/cds/vizier.22090005CDSShibayama T.Maehara H.Notsu S.Notsu Y.Nagao T.Honda S.,Ishii T.T.Nogami D.Shibata K.2017-12-22T05:33:44Z2013-12-13T11:28:46ZCDS support team

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

cds-question@unistra.frg-starsvariable-starsstellar-flaresBy extending our previous study by Maehara et al. (2012, Cat. J/other/Nat/485.478), we searched for superflares on G-type dwarfs (solar-type stars) using Kepler data for a longer period (500 days) than that (120 days) in our previous study. As a result, we found 1547 superflares on 279 G-type dwarfs, which is much more than the previous 365 superflares on 148 stars. Using these new data, we studied the statistical properties of the occurrence rate of superflares, and confirmed the previous results, i.e., the occurrence rate (dN/dE) of superflares versus flare energy (E) shows a power-law distribution with dN/dE{prop.to}E^-{alpha}^, where {alpha}~2. It is interesting that this distribution is roughly similar to that for solar flares. In the case of the Sun-like stars (with surface temperature 5600-6000K and slowly rotating with a period longer than 10 days), the occurrence rate of superflares with an energy of 10^34^-10^35^erg is once in 800-5000yr. We also studied long-term (500 days) stellar brightness variation of these superflare stars and found that in some G-type dwarfs the occurrence rate of superflares was extremely high, ~57 superflares in 500 days (i.e., once in 10 days). In the case of Sun-like stars, the most active stars show a frequency of one superflare (with 10^34^erg) in 100 days. There is evidence that these superflare stars have extremely large starspots with a size about 10 times larger than that of the largest sunspot. We argue that the physical origin of the extremely high occurrence rate of superflares in these stars may be attributed to the existence of extremely large starspots.2013ApJS..209....5Shttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJS/209/5CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toV/133 : Kepler Input Catalog (Kepler Mission Team, 2009)J/other/Nat/485.478 : Superflares on solar-type stars (Maehara+, 2012)J/AJ/142/112 : KIC photometric calibration (Brown+, 2011)J/AJ/141/50 : White-light flares on cool stars from Kepler (Walkowicz+, 2011)http://archive.stsci.edu/kepler/data_release.html : Kepler DR archivehttps://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJS/209/5https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJS/209/5http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJS/209/5https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJS/209/5https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJS/209/5http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJS/209/5GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/ApJS/209/5/stars (The 279 G-type dwarfs with superflares (table added by CDS))https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJS/209/5/stars?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJS/209/5/stars?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJS/209/5/stars?GETtext/xml+votable180.050000true291.0035737.437210.0055555555555555565/3690 3730 3741 3743 3778 3780 3783 3785 3786 6/14579 14580 14581 14582 14584 14585 14588 14589 14730 14735 14746 14753 14756 14757 14759 14764 14765 14767 14768 14770 14778 14779 14780 14781 14783 14794 14819 14824 14825 14826 14828 14915 14919 14924 14925 14928 14929 14931 14932 14933 14936 14937 14938 14940 14942 14943 14944 14945 14947 14948 14949 14950 14955 14957 14959 14960 14961 14962 14968 14969 15040 15041 15044 15057 15059 15060 15061 15104 15106 15108 15109 15110 15116 15118 15124 15126 15127 15128 15129 15131 15137 15139 15148 15150 15153 15154 15155 15156 15157 15158 15160 15168 15169 15170 15172 15174 15178https://cdsarc.cds.unistra.fr/viz-bin/moc/J/ApJS/209/5?format=asciiOpticaldefaultJ/ApJS/209/5/starsThe 279 G-type dwarfs with superflares (table added by CDS)recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintKIC[2012690/12401269] Kepler identifier (Cat. V/133)meta.id;meta.mainintprimaryNfNumber and link to flare observations (table7)meta.numberintnullableTeff[5101/5999] Effective temperatureKphys.temperature.effectiveintlog(g)[4/5] Log of the surface gravitylog(cm.s**-2)phys.gravityfloatRad[0.5/2] Stellar radiussolRadphys.size.radiusfloatKpmag[10.6/16.4] Kepler band magnitudemagphot.mag;em.optfloatProt[0.1/37]? Stellar rotational period (G1)dtime.periodfloatnullableFlCatDisplay other flares data from Kepler observations from Cat. J/other/Nat/485.478 and J/AJ/141/50meta.numberintnullableKIC*Details from the KIC catalog (V/133)meta.ref.urlcharSimbadSimbad column added by the CDSmeta.ref.urlchar_RAPositions from Kepler Input Catalog (Cat. V/133) (right ascension part)degpos.eq.ra;meta.main_DEPositions from Kepler Input Catalog (Cat. V/133) (declination part)degpos.eq.dec;meta.mainJ/ApJS/209/5/table7Parameters of the observed flaresDur[0.04/0.25] Duration (4)dtime.durationfloatrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintKIC[2012690/12401269] Kepler identifier (Cat. V/133)meta.id;meta.mainintBVAmp[0.0003/0.21] Brightness variation amplitude (2)arith.rate;src.var.amplitudefloatDateDate of flare peak; BJD-2400000dtime.epochdoubleFAmp[0.1/31] Flare amplitude (1)src.var.amplitudefloatE[1.2e+33/1.3e+36] Estimated bolometric flare energy; in erg units1e-07Jphys.energydouble