J/AJ/162/11ivo://CDS.VizieR/J/AJ/162/11doi:10.26093/cds/vizier.51620011CDSLin C.-L.Chen W.-P.Ip W.-H.Apai D.Bixel A.Boyle R.Chavez J.P.,Espinoza N.Gibbs A.Gabor P.Henning T.Mancini L.Rackham B.V.,Schlecker M.Dietrich J.Socia Q.J.Keppler M.Bhandare A.Haberle M.2022-03-16T12:09:17Z2021-11-18T07:45:10ZCDS support team

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

cds-question@unistra.frdwarf-starsexoplanetsstellar-flaresvisible-astronomyWe report the flare activity of Wolf359, the fifth closest star to the Sun and a candidate exoplanet-hosting M-dwarf. The star was a target of the Kepler/K2 mission and was observed by the EDEN project, a global network of 1-2m class telescopes for detection and characterization of rocky exoplanets in the habitable zones of late M-dwarfs within 50 light year from the solar system. In the combination of the archived K2 data and our EDEN observations, a total of 872 flares have been detected, 861 with the K2 (860 in the short-cadence and 18 in the long-cadence data, with 17 long-cadence events having short-cadence counterparts) and 11 with EDEN. Wolf 359 has relatively strong flare activity even among flaring M-dwarfs, in terms of the flare activity indicator (FA) defined as the integrated flare energy relative to the total stellar bolometric energy, where FA={sum}E_f_/{int}L_bol_dt~8.93x10^-5^ for the long-cadence flares, whereas for K2 short cadence and EDEN flares, the FA values are somewhat larger, FA~6.67 x 10^-4^ and FA~5.25x10^-4^, respectively. Such a level of activity, in accordance with the rotation period (P_rot_), suggests the star to be in the saturation phase. The size of the starspots is estimated to be at least 1.87%{+/-}0.59% of the projected disk area of Wolf359. We find no correlation of FA with the stellar rotational phase. Our analysis indicates a flare frequency distribution in a power-law form of dN/dE{prop}E^-{alpha}^ with {alpha}=2.13{+/-}0.14, equivalent to an occurrence rate of flares E_f_>~10^31^erg about once per day and of superflares with E_f_>~10^33^erg approximately 10 times per year. These superflares may impact the habitability of system in multiple ways, the details of which are topics for future investigations.2021AJ....162...11Lhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/AJ/162/11CatalogResearchIsServedByTAP VizieR generic servicerelated-toJ/AJ/140/1402 : M dwarf flares from SDSS spectra (Hilton+, 2010)J/ApJ/754/4 : HST monitoring of flaring stars in Galactic bulge (Osten+, 2012)J/ApJS/207/15 : M dwarf flare spectra (Kowalski+, 2013)J/MNRAS/445/2268 : Bayesian method for detecting stellar flares (Pitkin+, 2014)J/ApJ/829/23 : Stellar flares from Q0-Q17 Kepler LCs (Davenport, 2016)J/ApJS/232/26 : Catalog of Kepler flare stars (Van Doorsselaere+, 2017)J/ApJ/883/88 : Short-duration stellar flares GALEX & Kepler (Brasseur+, 2019)J/ApJ/890/46 : Superflares on solar-type stars from TESS first year (Tu+, 2020)J/MNRAS/505/L79 : Characteristic time of stellar flares (Yan+, 2021)J/other/CoSka/51.78 : Flare stars nearby Galactic open clusters (Maryeva+ 2021)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/AJ/162/11https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/AJ/162/11http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/AJ/162/11https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/AJ/162/11https://vizier.iucaa.in/viz-bin/votable?-source=J/AJ/162/11http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/AJ/162/11GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapOpticaldefaultJ/AJ/162/11/table2The flares observed on Wolf 359 by EDEN in this studyrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintFlare[0/10] Flare numbermeta.id;meta.mainintAf[0.01/0.32] Flare peak amplitudesrc.var.amplitudedoubleEflFlare energy in used band, ergs1e-07Jphys.energydoubleEfBolometric flare energy, ergs1e-07Jphys.energydoubleBJD[3681/3710] Time of flare peak; BJD-2454833dtime.epochdoubleDur[0.03/0.23] Duration of flarehtime.durationdoubleFlag[VR] Bandpass flagmeta.code.errorcharJ/AJ/162/11/table3The K2LC flares and their short cadence counterpartsrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintFlare[0/17] Flare numbermeta.id;meta.mainintAfLC[0.004/0.16] K2LC flare peak amplitude,src.var.amplitudedoubleEflLCK2LC flare energy Kepler band, ergs1e-07Jphys.energycharEfLCK2LC bolometric flare energy, ergs1e-07Jphys.energycharBJDLC[3078/3148] K2LC time of flare peak, BJD-2454833dtime.epochdoubleDurLC[1.47/21.1] K2LC duration of flarehtime.durationfloatAfSC[0.01/0.29]? K2SC flare peak amplitudesrc.var.amplitudedoublenullableEflSCK2SC flare energy Kepler band, ergs1e-07Jphys.energycharEfSCK2SC bolometric flare energy, ergs1e-07Jphys.energycharBJDSC[3078/3148]? K2SC time of flare peak, BJD-2454833dtime.epochdoublenullableDurSC[0.85/19]? K2SC duration of flarehtime.durationfloatnullableJ/AJ/162/11/table4Flares detected by K2 short cadence observations of Wolf 359recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintFlare[0/859] flare numbermeta.id;meta.mainintAf[0.002/1.93] flare peak amplitudesrc.var.amplitudedoubleEflFlare energy in the used band, {lambda}, ergs1e-07Jphys.energycharEfBolometric flare energy, ergs1e-07Jphys.energycharBJD[3072/3153] Time of flare peak, BJD-2454833dtime.epochdoubleDur[0.04/18.9] duration of flarehtime.durationfloatFlagFlare observed in LC data? Yes or Nometa.code.errorchar