J/MNRAS/447/2714ivo://CDS.VizieR/J/MNRAS/447/2714doi:10.26093/cds/vizier.74472714CDSBalona L.A.2024-08-14T20:19:42Z2015-09-10T09:01:11ZCDS support team

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

cds-question@unistra.frstellar-flaresvariable-starsFrom Kepler data, we show that the incidence of flares on stars drops by only a factor of 4 from K-M dwarfs to A-F stars. Allowing for visibility effects, this implies that the true relative number of flare stars does not change very much from cool dwarfs to hot A stars. The idea that flares on A stars can be attributed to a cool companion has to be rejected because it leads to flare amplitudes two orders of magnitude smaller than actually observed. We confirm that spots on flare stars are generally larger than those on non-flare stars and that flare stars rotate significantly faster than non-flare stars. Analysis of 209 flare stars observed in Kepler short-cadence mode allows accurate measurements of flare shapes and duration. We find that about one-third of the flares have a bump or slope discontinuity on the decaying branch and that flares of long duration are to be found in stars with low surface gravities. Flare energies are strongly correlated with stellar luminosity and radius. The correlation with radius leads to a rough estimate of several tens of gauss for the typical magnetic field associated with a flare. The correlation with stellar luminosity can be understood if the typical flare loop length-scales approximately as the stellar radius. We examined the flare frequency as a function of orbital phase in three eclipsing binaries in which a large number of flares are visible. There appears to be no correlation of flaring with orbital phase, which weakens the hypothesis that flares in close binaries could be a result of reconnection of field lines connecting the two stars.2015MNRAS.447.2714Bhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/MNRAS/447/2714CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toV/133 : Kepler Input Catalog (Kepler Mission Team, 2009)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/MNRAS/447/2714https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/MNRAS/447/2714http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/MNRAS/447/2714https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/MNRAS/447/2714https://vizier.iucaa.in/viz-bin/votable?-source=J/MNRAS/447/2714http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/MNRAS/447/2714GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/MNRAS/447/2714/table2 (Flare stars observed in SC mode, stellar parameters)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/MNRAS/447/2714/table2?https://vizier.iucaa.in/viz-bin/conesearch/J/MNRAS/447/2714/table2?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/MNRAS/447/2714/table2?GETtext/xml+votable180.050000true291.0336936.771041940.0055555555555555565/3646 3732 3784 6/14567 14573 14577-14580 14582-14583 14589-14591 14733 14735 14744 14746 14750-14754 14757 14760-14761 14763-14765 14768-14769 14771-14772 14774-14777 14779 14781-14783 14792 14794 14824 14826 14915 14917-14919 14921 14923-14924 14933-14936 14939 14942 14947-14948 14950 14955 14958-14960 14962-14963 14966-14969 14972 15040 15044-15045 15057 15060 15104 15106-15107 15109 15112-15114 15116 15118-15122 15126 15128-15129 15131-15133 15141-15144 15147-15149 15153-15154 15156 15159-15160 15169-15170 15172-15173 15178https://cdsarc.cds.unistra.fr/viz-bin/moc/J/MNRAS/447/2714?format=asciiOpticaldefaultJ/MNRAS/447/2714/table2Flare stars observed in SC mode, stellar parametersrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintKICKIC numbermeta.id;meta.mainintkepmagKepler magnitudemagphot.mag;em.optfloatTeffEffective temperatureKphys.temperature.effectiveintloggSurface gravitylog(cm.s**-2)phys.gravityfloatTypeVariable type (1)meta.code;src.varcharProt? Rotation perioddtime.periodfloatnullableu_ProtUncertainty flag on Protmeta.code.errorcharPorb? Orbital perioddtime.perioddoublenullableNotesNotesmeta.notecharkicDisplay the KIC data (2009, Cat. V/133)meta.ref.urlcharSimbadSimbad column added by the CDSmeta.ref.urlchar_RAPositions form KIC catalog (2009, Cat. V/133) (right ascension part)degpos.eq.ra;meta.main_DEPositions form KIC catalog (2009, Cat. V/133) (declination part)degpos.eq.dec;meta.mainJ/MNRAS/447/2714/table3Flare stars observed in SC mode, parameters of the strongest flare in each starrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintKICKepler Input Catalog identifiermeta.id;meta.mainintlog(EW)Total integrated flux of the flare (G1)log(h)phot.flux;arith.ratiofloatlog(DF/F)Relative flare intensityspect.line.intensity;arith.ratiofloatDtTotal flare durationlog(h)time.durationfloatlog(E)Flare energylog(1e-07W)phys.energyfloatfFlare frequency (in flare/d)d**-1em.freqfloatNFlareNumber of flaresmeta.numberintJ/MNRAS/447/2714/table1Parameters of flares measured in short-cadence Kepler observations for 209 starsrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintKICKepler Input Catalog identifiermeta.id;meta.maininttmaxTime of flare maximum (BJD-2450000)dtime.epochdoublelog(EW)Total integrated flux of the flare (G1)log(h)phot.flux;arith.ratiofloatlog(DF/F)Relative flare intensityspect.line.intensity;arith.ratiofloatDtTotal flare durationlog(h)time.durationfloatlog(E)Flare energylog(1e-07W)phys.energyfloat