J/A+A/637/A22ivo://CDS.VizieR/J/A+A/637/A22doi:10.26093/cds/vizier.36370022CDSRaetz S.Stelzer B.Damasso M.Scholz A.2022-06-23T07:50:24Z2020-05-06T06:43:16ZCDS support team

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

cds-question@unistra.frlate-type-starsstellar-flaresUsing light curves obtained by the K2 mission, we study the relation between stellar rotation and magnetic activity with a special focus on stellar flares. Our sample comprises 56 bright and nearby M dwarfs observed by K2 during campaigns C0-C18 in long and short cadence mode. We derive rotation periods for 46 M dwarfs and measure photometric activity indicators such as amplitude of the rotational signal, standard deviation of the light curves, and the basic flare properties (flare rate, flare energy, flare duration, flare amplitude). We found 1662 short cadence flares of which 363 have a long cadence counterpart with flare energies up to 5.6*10^34^erg. The flare amplitude, duration and flare frequency derived from the short cadence LCs differ significantly from the ones derived from the long cadence data. The analysis of the short cadence light curves results in a 4.6 times higher flare rate than the long cadence data. We confirm the abrupt change of the activity level in the rotation-activity relation at a critical period of ~10d when photometric activity diagnostics are used. This change is most drastic in the flare duration and the flare frequency for short cadence data. Our flare studies revealed that the highest flare rates are not found among the fastest rotators and that the stars with the highest flare rates do not show the most energetic flares. We found a ~2 times larger superflares frequency (>5*10^34^erg) for the fast rotating M stars than for solar like stars in the same period range. By fitting the cumulative flare frequency distribution we derived a power-law index of alpha=1.84+/-0.14 consistent with previous M dwarf studies and the value found for the Sun.2020A&A...637A..22Rhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/637/A22CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toIV/34 : K2 Ecliptic Plane Input Catalog (EPIC) (Huber+, 2017)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/637/A22https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/637/A22http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/637/A22https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/637/A22https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/637/A22http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/637/A22GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/A+A/637/A22/tableb (Stellar parameters (tableb1) and rotation period and activity indicators obtained in short and long cadence LCs (table B2) in our K2 M dwarf sample)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/637/A22/tableb?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/637/A22/tableb?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/637/A22/tableb?GETtext/xml+votable180.050000true96.5605823.82730.0055555555555555566/260 304 307 4295 4520 4672 4693 4696 4708 4716 17288 18588 23487 23532 23548 23857 24040 24103 25619 25637 25639 25653 25656 25659 25677-25678 25702 25708 25713 25718 25727 25733 25747 25750 25792 25794-25795 25810 25814 25820 25840 25843 25846 25849-25850 26178 26192 26299 27000 27456 30729 44728https://cdsarc.cds.unistra.fr/viz-bin/moc/J/A+A/637/A22?format=asciidefaultJ/A+A/637/A22/tablebStellar parameters (tableb1) and rotation period and activity indicators obtained in short and long cadence LCs (table B2) in our K2 M dwarf samplerecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintEPICEPIC identification numbermeta.id;meta.mainlongCampaignK2 observing campaignmeta.id;obscharKpmagApparent magnitude in the Kepler bandmagphot.mag;em.optfloatlogL(Kp0)Quiescent luminosity in the Kepler band, logL(Kp,0)log(1e-07W)phys.luminosityfloatKsMAGAbsolute magnitude in the 2MASS K-bandmagphys.magAbsfloate_KsMAGUncertainty on MKsmagstat.errorfloatRsStellar radiussolRadphys.size.radiusfloate_RsUncertainty on stellar radiussolRadstat.errorfloatMsStellar masssolMassphys.massfloate_MsUncertainty on stellar masssolMassstat.errorfloatTeffEffective temperatureKphys.temperature.effectiveinte_TeffUncertainty on effective temperatureKstat.error;phys.temperature.effectiveintdDistancepcpos.distancefloate_dUncertainty on distancepcstat.errorfloatSpTypeSpectral type given as subclass of M dwarfs (negative values correspond to spectral types earlier than M)src.spTypefloatProt? Stellar rotation perioddtime.periodfloatnullableRper? Full amplitude of the rotation signal%stat.snr;src.var.amplitudefloatnullablelogE(Fmax)? Maximum flare energy, logE(F,max)log(1e-07J)phys.energy;stat.maxfloatnullableSphStandard deviation of the full light curve(10-6)stat.stdevintSflat(SC)Standard deviation of the flattened and cleaned short cadence light curve(10-6)stat.stdevintSimbadSimbad column added by the CDSmeta.ref.urlcharNflares(SC)Number of short cadence flaresmeta.numberintnu(SC)? Flare frequency in short cadence, in Nfares/d unitd**-1em.freq;src.varfloatnullableSflat(LC)Standard deviation of the flattened and cleaned long cadence light curve(10-6)stat.stdevintNflares(LC)Number of long cadence flaresmeta.numberintnu(LC)? Flare frequency in long cadence, in Nfares/d unitd**-1em.freq;src.varfloatnullable_RAPositions from EPIC catalog, IV/34 (right ascension part)degpos.eq.ra;meta.main_DEPositions from EPIC catalog, IV/34 (declination part)degpos.eq.dec;meta.main