J/ApJ/902/115ivo://CDS.VizieR/J/ApJ/902/115doi:10.26093/cds/vizier.19020115CDSHoward W.S.Corbett H.Law N.M.Ratzloff J.K.Galliher N.,Glazier A. LGonzalez R.Vasquez Soto A.Fors O.del Ser D.Haislip J.2022-09-30T22:14:20Z2022-05-11T14:33:44ZCDS support team

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

cds-question@unistra.frstellar-flaresm-starstwo-color-diagramseffective-temperaturestellar-massesvisible-astronomySuperflares may provide the dominant source of biologically relevant UV radiation to rocky habitable-zone M-dwarf planets (M-Earths), altering planetary atmospheres and conditions for surface life. The combined line and continuum flare emission has usually been approximated by a 9000K blackbody. If superflares are hotter, then the UV emission may be 10 times higher than predicted from the optical. However, it is unknown for how long M-dwarf superflares reach temperatures above 9000K. Only a handful of M-dwarf superflares have been recorded with multiwavelength high-cadence observations. We double the total number of events in the literature using simultaneous Evryscope and Transiting Exoplanet Survey Satellite observations to provide the first systematic exploration of the temperature evolution of M-dwarf superflares. We also increase the number of superflaring M-dwarfs with published time-resolved blackbody evolution by ~10x. We measure temperatures at 2 minutes cadence for 42 superflares from 27 K5-M5 dwarfs. We find superflare peak temperatures (defined as the mean of temperatures corresponding to flare FWHM) increase with flare energy and impulse. We find the amount of time flares emit at temperatures above 14000K depends on energy. We discover that 43% of the flares emit above 14000K, 23% emit above 20000K and 5% emit above 30000K. The largest and hottest flare briefly reached 42000K. Some do not reach 14000 K. During superflares, we estimate M-Earths orbiting <200 Myr stars typically receive a top-of-atmosphere UV-C flux of ~120W/m^2^ and up to 10^3^W/m^2^, 100-1000 times the time-averaged X-ray and UV flux from Proxima Cen.2020ApJ...902..115Hhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/902/115CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toI/347 : Distances to 1.33 billion stars in Gaia DR2 (Bailer-Jones+, 2018)IV/38 : TESS Input Catalog - v8.0 (TIC-8) (Stassun+, 2019)IV/39 : TESS Input Catalog version 8.2 (TIC v8.2) (Paegert+, 2021)J/AJ/132/866 : New M dwarfs in solar neighborhood (Riaz+, 2006)J/A+A/460/695 : Search for Associations Containing Young stars (Torres+, 2006)J/AJ/134/2340 : Membership of Praesepe & Coma Berenices (Kraus+, 2007)J/ApJS/207/15 : M dwarf flare spectra (Kowalski+, 2013)J/MNRAS/443/2561 : CONCH-SHELL catalog of nearby M dwarfs (Gaidos+, 2014)J/AJ/147/146 : Spectroscopy of Tuc-Hor candidate members (Kraus+, 2014)J/ApJ/788/81 : BANYAN III. RVel and rotation of low-mass stars (Malo+, 2014)J/ApJ/809/77 : Transiting Exoplanet Survey Satellite (TESS) (Sullivan+, 2015)J/A+A/600/A13 : HARPS M dwarfs magnetic activity (Astudillo-Defru+, 2017)J/ApJ/834/85 : H{alpha} emission in nearby M dwarfs (Newton+, 2017)J/ApJ/840/87 : Young star systems observed with SALT (Riedel+, 2017)J/ApJ/856/23 : BANYAN. XI. The BANYAN {Sigma} algorithm (Gagne+, 2018)J/A+A/615/A172 : alpha Cen A and B chemical composition (Morel, 2018)J/ApJ/867/105 : ATLAS all-sky stellar ref. cat., ATLAS-REFCAT2 (Tonry+, 2018)J/ApJ/883/88 : Short-duration flares from GALEX & Kepler (Brasseur+, 2019)J/ApJ/881/9 : EvryFlare. I. Cool stars's flares (Howard+, 2019)J/A+A/622/A133 : M45, M44 and M67 flare stars (Ilin+, 2019)J/AJ/159/60 : Flares from 1228 stars in TESS sectors 1 & 2 (Gunther+, 2020)J/ApJ/895/140 : EvryFlare. II. Param. of 122 cool flare stars (Howard+, 2020)J/ApJ/890/23 : NUV and FUV measurements of planet host stars (Loyd+, 2020)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJ/902/115https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJ/902/115http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJ/902/115https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJ/902/115https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJ/902/115http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJ/902/115GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/ApJ/902/115/table1 (Temperatures of simultaneous flares observed during TESS Cycle 1)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJ/902/115/table1?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJ/902/115/table1?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJ/902/115/table1?GETtext/xml+votable180.050000true71.0457397-70.32345580.0055555555555555566/16525 17139 33075 33320 33464 33523 33531 33550 33579 33583 33838 33894 33937 34377 34830 34998 37379 40275 41591 45269 45336 45389 45471 46148 46351 46598 46717 46723 48263https://cdsarc.cds.unistra.fr/viz-bin/moc/J/ApJ/902/115?format=asciiOpticaldefaultJ/ApJ/902/115/table1Temperatures of simultaneous flares observed during TESS Cycle 1recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintTIC[5796048/441398770] TESS Input catalog IDmeta.id;meta.mainlongm_TICNumber of flares for this starmeta.numberintnullableDateObservation date and time (ISO 8601, UTC) (1)stime.epoch;obsnullablelogEg'[31.2/35.1] Evryscope flare energy (erg)log(1e-07J)phys.energyfloatlogET[31.25/35] TESS flare energy (erg)log(1e-07J)phys.energyfloatg'Amp[0.08/7.3] Evryscope amplitude in normalized flux, A_g'_ ({Delta}F/F)phot.flux;arith.ratiofloatSimbadSimbad column added by the CDSmeta.ref.urlcharTAmp[0.01/0.65] TESS amplitude in normalized flux, A_T_ ({Delta}F/Fphot.flux;arith.ratiofloatColor[0.07/6.6] Flare color between normalized-flux amplitudes (A_g'_-A_T_)magphot.color;em.opt;em.optfloate_Color[0.003/0.6] Uncertainty in Colormagstat.error;phot.colorfloatTeffPk[2700/43200] Peak temperature, avg. temperature in FWHMKphys.temperatureinte_TeffPk[300/3300] Uncertainty in TeffPkKstat.errorintTeffTot[2600/50000] Total temperatureKphys.temperatureinte_TeffTot[200/13400]? Lower uncertainty in TeffTotKstat.errorintnullableE_TeffTot[200/17100]? Upper uncertainty in TeffTotKstat.error;stat.maxintnullabletAbv[0/19.2] Time spent above 14000Kmintime.epochfloatImpulse[0.003/1.3] Impulse, normalized Everyscope flux amplitude A_g'_ / minute (2)src.var.amplitude;arith.ratiofloate_Impulse[0/0.6] Uncertainty in Impulsestat.errorfloatProt[0.11/83]? Stellar rotation perioddtime.perioddoublenullableMass[0.13/0.7] Stellar masssolMassphys.massfloat_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.main