J/ApJ/858/55ivo://CDS.VizieR/J/ApJ/858/55doi:10.26093/cds/vizier.18580055CDSPaudel R.R.Gizis J.E.Mullan D.J.Schmidt S.J.Burgasser A.J.,Williams P.K.G.Berger E.2019-07-30T08:19:53Z2019-05-03T10:44:32ZCDS support team

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

cds-question@unistra.frstellar-flaresl-dwarfsstellar-distancebrown-dwarfsWe report the white light flare rates for 10 ultracool dwarfs using Kepler K2 short-cadence data. Among our sample stars, two have spectral type M6, three are M7, three are M8, and two are L0. Most of our targets are old low-mass stars. We identify a total of 283 flares in all of the stars in our sample, with Kepler energies in the range log E_Kp_~(29-33.5)erg. Using the maximum-likelihood method of line fitting, we find that the flare frequency distribution (FFD) for each star in our sample follows a power law with slope -{alpha} in the range -(1.3-2.0). We find that cooler objects tend to have shallower slopes. For some of our targets, the FFD follows either a broken power law, or a power law with an exponential cutoff. For the L0 dwarf 2MASSJ12321827-0951502, we find a very shallow slope (-{alpha}=-1.3) in the Kepler energy range (0.82-130)x10^30^erg: this L0 dwarf has flare rates which are comparable to those of high-energy flares in stars of earlier spectral types. In addition, we report photometry of two superflares: one on the L0 dwarf 2MASS J12321827-0951502 and another on the M7 dwarf 2MASS J08352366+1029318. In the case of 2MASSJ12321827-0951502, we report a flare brightening by a factor of ~144 relative to the quiescent photospheric level. Likewise, for 2MASSJ08352366+1029318, we report a flare brightening by a factor of ~60 relative to the quiescent photospheric level. These two superflares have bolometric (ultraviolet/optical/infrared) energies 3.6x10^33^erg and 8.9x10^33^erg respectively, while the full width half maximum timescales are very short, ~2min. We find that the M8 star TRAPPIST-1 is more active than the M8.5 dwarf 2M03264453+1919309, but less active than another M8 dwarf (2M12215066-0843197).2018ApJ...858...55Phttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/858/55CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toV/133 : Kepler Input Catalog (Kepler Mission Team, 2009)IV/34 : K2 Ecliptic Plane Input Catalog (EPIC) (Huber+, 2017)J/ApJ/564/421 : Spectra of T dwarfs. I. (Burgasser+, 2002)J/AJ/126/2421 : 2MASS-Selected sample of ultracool dwarfs (Cruz+, 2003)J/AJ/136/1290 : Ultracool dwarfs from the 2MASS (Reid+, 2008)J/AJ/137/1 : PMs and astrometry of late-type dwarfs (Faherty+, 2009)J/AJ/139/1808 : Colors and kinematics of SDSS L dwarfs (Schmidt+, 2010)J/AJ/141/50 : White-light flares on cool Kepler stars (Walkowicz+, 2011)J/ApJS/201/19 : Hawaii Infrared Parallax Program. I. (Dupuy+, 2012)J/other/Nat/485.478 : Superflares on solar-type stars (Maehara+, 2012)J/ApJ/754/4 : HST monitoring of flaring stars in the bulge (Osten+, 2012)J/ApJ/750/99 : The Pan-STARRS1 photometric system (Tonry+, 2012)J/MNRAS/428/2824 : Rapid optical variability in ultracool dwarfs (Koen, 2013)J/ApJS/209/5 : Superflares of Kepler stars. I. (Shibayama+, 2013)J/ApJ/798/73 : BANYAN All-Sky Survey (BASS) catalog. V. YMGs (Gagne+, 2015)J/AJ/149/158 : The BUD sample. I. L dwarf activity sample (Schmidt+, 2015)J/ApJS/224/37 : White-light flares on close bin. from Kepler (Gao+, 2016)J/ApJ/829/23 : Stellar flares from Q0-Q17 Kepler LCs (Davenport, 2016)J/ApJ/817/112 : NEOWISE/AllWISE high PM objects (Schneider+, 2016)J/AJ/152/24 : Trigonometric plx of 134 low-mass stars (Weinberger+, 2016)J/ApJ/849/36 : Flaring activity of M dwarfs in Kepler field (Yang+, 2017)J/ApJS/232/26 : Catalog of Kepler flare stars (Van Doorsselaere+, 2017)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJ/858/55https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJ/858/55http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJ/858/55https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJ/858/55https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJ/858/55http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJ/858/55GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/ApJ/858/55/targets (Properties and median fluxes of targets (Tables 1 and 2))https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJ/858/55/targets?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJ/858/55/targets?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJ/858/55/targets?GETtext/xml+votable180.050000true337.2264536-13.42207190.0055555555555555566/410 4274 18478 18482 18571 18726 25433 25456 25818 26300https://cdsarc.cds.unistra.fr/viz-bin/moc/J/ApJ/858/55?format=asciidefaultJ/ApJ/858/55/targetsProperties and median fluxes of targets (Tables 1 and 2)recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintName2MASS namemeta.idcharONameOther namemeta.idcharEPIC[200164267/228754562] EPIC number (1)meta.id;meta.mainlongprimaryKpmag[14.6/19] Kepler magnitudemagphot.mag;em.optfloatJmag[10.7/13.8] J-band magnitudemagphot.mag;em.IR.JfloatCam[3/12] K2 campaign number in which the target was observedmeta.id;obsintVtan[5/61] Tangential velocity V_tan_ (2)km/sphys.veloc.transversefloatSpTMK optical spectral typesrc.spTypecharDist[11.2/34] Distance (d)pcpos.distance;pos.heliocentricfloate_Dist[0.4/6.3] Dist uncertaintypcstat.errorfloatf_DistFlag on Dist (3)meta.codecharRef[1/6] Reference used to identify the spectral types (4)meta.refintNflNumber of flare measurements (link to Table 3)meta.numberintnullableSimbadSimbad column added by the CDSmeta.ref.urlcharMedFlux2[358/16463] Median count rate within 2 pixel radius aperturect/sarith.rate;phot.count;stat.medianintMedFlux3[381/18063] Median count rate within 3 pixel radius aperturect/sarith.rate;phot.count;stat.medianint_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.mainJ/ApJ/858/55/table3Flare propertiesrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintEPIC[200164267/228754562] Kepler identifiermeta.id;meta.mainlongPTime[2144.8/2982] Peak flux time during flare, Barycentric Julian Date; JD-2454833dphot.flux;stat.maxdoubleDur[0.6/41000] Equivalent duration of flarestime.durationfloatlogE[29.3/33.5] log of Kepler energy of flare; in units of ergs.log(1e-07J)phys.energyfloat