J/ApJ/883/88ivo://CDS.VizieR/J/ApJ/883/88doi:10.26093/cds/vizier.18830088CDSBrasseur C.E.Osten R.A.Fleming S.W.2021-09-16T14:04:51Z2021-03-23T13:59:08ZCDS support team

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

cds-question@unistra.frstellar-flaresstellar-distancestellar-radiiultraviolet-astronomyvisible-astronomyg-starsWe report on a population of short-duration near-ultraviolet (NUV) flares in stars observed by the Kepler and Galaxy Evolution Explorer (GALEX) missions. We analyzed the NUV light curves of 34276 stars observed from 2009 to 2013 by both the GALEX (NUV) and Kepler (optical) space missions with the eventual goal of investigating multiwavelength flares. From the GALEX data, we constructed light curves with a 10s cadence, and we ultimately detected 1904 short-duration flares on 1021 stars. The vast majority (94.5%) of these flares have durations less than 5 minutes, with flare flux enhancements above the quiescent flux level ranging from 1.5 to 1700. The flaring stars are primarily solar-like, with Teff ranging from 3000 to 11000K and radii between 0.5 and 15R_{sun}_. This set of flaring stars is almost entirely distinct from that of previous flare surveys of Kepler data and indicates a previously undetected collection of small flares contained within the Kepler sample. The range in flare energies spans 1.8x10^32^-8.9x10^37^erg, with associated relative errors spanning 2%-87%. The flare frequency distribution by energy follows a power law with index {alpha}=1.72+/-0.05, consistent with results of other solar and stellar flare studies at a range of wavelengths. This supports the idea that the NUV flares we observed are governed by the same physical processes present in solar and optical flares. The relationship between flare duration and associated flare energy extends results found for solar and stellar white-light flares, and suggests that these flares originate in regions with magnetic field strengths of several hundred Gauss, and length scales of the order of 10^10^cm.2019ApJ...883...88Bhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/883/88CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toV/133 : Kepler Input Catalog (Kepler Mission Team, 2009)II/335 : Revised catalog of GALEX UV sources (GUVcat_AIS GR6+7) (Bianchi+ 2017)I/345 : Gaia DR2 (Gaia Collaboration, 2018)I/347 : Distances to 1.33 billion stars in Gaia DR2 (Bailer- Jones+, 2018)J/ApJ/448/683 : Hyades RASS observations (Stern+ 1995)J/AJ/142/112 : KIC photometric calibration (Brown+, 2011)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/ApJS/207/15 : M dwarf flare spectra (Kowalski+, 2013)J/ApJS/209/5 : Superflares of Kepler stars. I. (Shibayama+, 2013)J/ApJS/211/2 : Stellar properties of Q1-16 Kepler targets (Huber+, 2014)J/ApJS/211/24 : Rotation periods of Kepler MS stars (McQuillan+, 2014)J/MNRAS/447/2714 : Flare stars across the H-R diagram (Balona+, 2015)J/ApJ/813/100 : Deep GALEX NUV survey of Kepler field. I. (Olmedo+, 2015)J/ApJ/829/23 : Stellar flares from Q0-Q17 Kepler LCs (Davenport, 2016)J/ApJ/851/91 : Studies of solar white-light flares (Namekata+, 2017)J/ApJ/866/99 : Radii of KIC stars & planets using Gaia DR2 (Berger+, 2018)J/A+A/620/A55 : Magnetic flaring from PMS stars spectra (Flaccomio+, 2018)J/ApJ/858/55 : K2 ultracool dwarfs survey. III. Flares (Paudel+, 2018)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJ/883/88https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJ/883/88http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJ/883/88https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJ/883/88https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJ/883/88http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJ/883/88GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/ApJ/883/88/table2 (All detected and vetted flares with calculated energies for 942 KIC stars)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJ/883/88/table2?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJ/883/88/table2?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJ/883/88/table2?GETtext/xml+votable180.050000true285.3867845.59402810.0055555555555555565/3646 3741-3743 3777-3778 3782 3784-3786 3792 6/14567 14573 14583 14591 14752 14754 14759 14770 14779 14782 14828 14830 14914-14915 14933 14937 14939 14942-14943 14946-14947 14949-14950 14952 14956 14958-14960 15044-15045 15057 15059-15062 15105 15107 15118-15122 15124 15132-15134 15148 15172 15232https://cdsarc.cds.unistra.fr/viz-bin/moc/J/ApJ/883/88?format=asciiUVOpticaldefaultJ/ApJ/883/88/table2All detected and vetted flares with calculated energies for 942 KIC starsrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintKICKepler Input Catalog ID number of starmeta.id;meta.mainintGIDGALEX Catalog ID number of starmeta.id.crossStart[926132291/999944565] Start time of flare (1)time.epochlongEnd[926132401/999944606] End time of flare (1)time.epochlongDist[58/11000] Estimated distance (2)pcpos.distance;pos.heliocentricfloate_Dist[57/9100] Lower bound of Dist (2)pcstat.errorfloatE_Dist[58/14000] Upper bound of Dist (2)pcstat.error;stat.maxfloatRad[0.47/15]? Stellar radius (3)solRadphys.size.radiusfloatnullableTeff[3519/11928]? Effective temperature (4)Kphys.temperature.effectiveintnullableQFlux[1e-17/2.4e-14] Quiescent flux; in erg/s/cm^2^/{AA} units (5)cW.m**-2.nm**-1meta.unitdoublee_QFlux[3e-18/5e-16] Standard error of the mean in QFluxcW.m**-2.nm**-1stat.errorfloatLum[2e+28/9.5e+33] NUV stellar luminosity; erg/s1e-07Wphys.luminositydoublee_Lum[3e+27/2e+33] Uncertainty in Lum1e-07Wstat.errorfloatEbol[1.8e+32/9e+37] Estimated bolometric energy; in erg units1e-07Jphys.energyfloate_Ebol[1.6e+32/5.6e+37] Lower bound of Ebol (6)1e-07Jstat.errorfloatE_Ebol[2e+32/1.4e+38] Upper bound of Ebol (7)1e-07Jstat.error;stat.maxfloatO15Display data from Olmedo+, 2015, J/ApJ/813/100meta.ref.urlintnullableH14Display the Kepler data from Huber+, 2014, J/ApJS/211/2meta.ref.urlcharGaiaDisplay the Gaia DR2 (I/345) and Bailer-Jones+ (2018, I/347) data within 3"meta.ref.urlcharSimbadSimbad column added by the CDSmeta.ref.urlchar_RAPosition from KIC catalog (V/133) (right ascension part)degpos.eq.ra;meta.main_DEPosition from KIC catalog (V/133) (declination part)degpos.eq.dec;meta.main