J/ApJ/961/130ivo://CDS.VizieR/J/ApJ/961/130CDSZhao Z.H.Hua Z.Q.Cheng X.Li Z.Y.Ding M.D.2026-05-27T08:21:11Z2026-05-27T09:16:41ZCDS support team

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

cds-question@unistra.frstellar-flaresx-ray-sourcesphotometryvisible-astronomytwo-color-diagramsstellar-distanceThe statistical characteristics of stellar flares at optical bands have received extensive study, but they remain to be studied at soft X-ray bands, in particular for solar-type stars. Here, we present a statistical study of soft X-ray flares on solar-type stars, which can help in understanding the multiwavelength behaviors of stellar flares. We mainly use Chandra Source Catalog Release 2.0, which includes a number of flaring stars with denoted variability, and Gaia Data Release 3, which includes the necessary information for classifying stars. We also develop a set of methods for identifying and classifying stellar soft X-ray flares and estimating their properties. A detailed statistical investigation of 129 flare samples on 103 nearby solar-type stars as selected yields the following main results. (1) The flare energy emitted at the soft X-ray band in our sample ranges from ~10^33^ to ~10^37^erg, and the majority of them are superflares, with the most energetic one having energy of 6.0_-4.7_^+3.2^x10^37^erg. (2) The flare duration is related to its energy as formulated by T_duration,SXR_{propto}E_flare,SXR_^0.201+/-0.024^, which is different from those derived at optical and near-IR bands, indicating distinct radiation mechanisms at different bands. (3) The frequency distribution of stellar flares as a function of energy is formulated as dN_flare_/dE_flare,SXR_{propto}E_flare,SXR_^-1.77^, which is similar to the results found at other bands and on other types of stars, indicating that the energy emitted at the soft X-ray band could be a constant fraction of the full-band bolometric energy.2024ApJ...961..130Zhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/961/130CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toIX/57 : The Chandra Source Catalog (CSC), Release 2.0 (Evans+, 2019)I/352 : Distances to 1.47 billion stars in Gaia EDR3 (Bailer-Jones+, 2021)I/355 : Gaia DR3 Part 1. Main source (Gaia Collaboration, 2022)J/ApJ/675/1254 : M37 variable stars (Hartman+, 2008)J/other/Nat/485.478 : Superflares on solar-type stars (Maehara+, 2012)J/ApJS/209/5 : Superflares of Kepler stars. I. (Shibayama+, 2013)J/A+A/581/A28 : Stellar X-ray flares from the 2XMM catalog (Pye+, 2015)J/ApJ/851/91 : Stat. studies of solar white-light flares (Namekata+, 2017)J/ApJ/849/36 : Flaring activity of M dwarfs in Kepler field (Yang+, 2017)J/A+A/620/A55 : Magnetic flaring from PMS stars spectra (Flaccomio+, 2018)J/MNRAS/494/3596 : Superflares in solar-type stars with TESS (Doyle+, 2020)J/ApJ/890/46 : Superflares on solar-type stars from TESS 1st yr (Tu+, 2020)J/ApJ/916/32 : X-ray superflares from PMS stars (Getman+, 2021)J/MNRAS/517/2925 : ORB6 binaries in Gaia EDR3 (Chulkov+, 2022)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJ/961/130https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJ/961/130http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJ/961/130https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJ/961/130https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJ/961/130http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJ/961/130GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/ApJ/961/130/table34 (Physical and observational properties of host stars and properties of stellar flares (Tables 3 and 4))https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJ/961/130/table34?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJ/961/130/table34?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJ/961/130/table34?GETtext/xml+votable180.050000true88.0019632.613380.0055555555555555566/206 1539 2708 3063 3093 3256 3389 4410 6761 11425 13050 14305 14442 14690 14692-14693 14696 15511 15683 16713 21438-21439 21643 22252 22873 23637 24345 24451 24522 24740 25083 28717 28768 28827 28830 28890-28891 28896 28970 29100 29184 29259 29508 30366 30616 31509 33095 34264 34534 37333 37335 37343 37388 37871 37881 37915 37924 37926 37933 37937 38016 38026 39241 41576 41586 41591 41685 41812 42370 42382 42394 42434 42463 42666 42955 42981 43246 45984 478281.9867573869263685e-19 3.916500758235022e-19https://cdsarc.cds.unistra.fr/viz-bin/moc/J/ApJ/961/130?format=asciiX-rayOpticaldefaultJ/ApJ/961/130/table34Physical and observational properties of host stars and properties of stellar flares (Tables 3 and 4)recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintGaiaDisplay data from Gaia DR3 (I/355) within 1"meta.ref.urlcharLCLight curve categories (1)meta.codecharSeq[0/128] Running sequence numbermeta.id;meta.mainintObsID[606/16444] Chandra observation identifiermeta.id;obs.param;obsintRAJ2000[6.2/346] CSC 2.0 Right Ascension (J2000)degpos.eq.ra;meta.mainDEJ2000[-74.3/65] CSC 2.0 Declination (J2000)degpos.eq.dec;meta.mainDist[0.066/2.43] Gaia DR3 distancekpcpos.distancedoublee_Dist[4.9e-05/0.45] Uncertainty in Distkpcstat.error;pos.distancedoubleTeff[5110/5990] Gaia DR3 effective temperatureKphys.temperature.effectiveintlogg[4/4.8] Gaia DR3 log surface gravitylog(cm.s**-2)phys.gravityfloatTime[10044/175692] Total elapsed time of observation from CSC 2.0 (gti_elapse)stime.intervalintBp-Rp[0.76/3.16] Gaia DR3 Blue-Red passband colormagphot.color;em.opt.B;em.opt.RfloatGmag[9.3/17.31] Gaia DR3 mean G band magnitudemagphot.mag;em.optfloatRUWE[0.73/5.86] Gaia DR3 renormalized unit weight errorstat.errorfloatTRise[0/42756] Chandra soft X-ray band flare rise timestime.epochintTDecay[0/30118] Chandra soft X-ray band flare decay timestime.epochintRatio[0/70.76] The TDecay/TRise ratiotime;arith.ratiofloatTDur[89/71315] Chandra soft X-ray band flare durationstime.durationintCRquies[0.00015/0.2] Chandra soft X-ray band quiescent count ratect/sphot.count;em.X-ray.softdoubleCRpeak[0.003/1.3] Chandra soft X-ray band flare peak count ratect/sphot.count;em.X-ray.softdoubleFPeak[3e-14/1.62e-10]? Chandra soft X-ray band flare peak flux; erg/s/cm^2^mW.m**-2phot.flux;em.X-ray.softdoublenullablee_FPeak[1e-14/5.3e-11]? Lower uncertainty in FPeakmW.m**-2stat.error;phot.flux;em.X-ray.softdoublenullableE_FPeak[4.6e-14/1.1e-10]? Upper uncertainty in FPeakmW.m**-2stat.error;phot.flux;em.X-ray.softdoublenullableLPeak[1e+29/1e+34]? Chandra soft X-ray band flare peak luminosity; erg/s1e-07Wphys.luminosity;em.X-ray.softdoublenullablee_LPeak[5e+28/1e+34]? Lower uncertainty in LPeak1e-07Wstat.error;phys.luminosity;em.X-ray.softdoublenullableE_LPeak[2.3e+29/1.8e+34]? Upper uncertainty in LPeak1e-07Wstat.error;phys.luminosity;em.X-ray.softdoublenullableEFlare[9e+32/6e+37]? Chandra soft X-ray band flare energy; erg1e-07Jphys.energy;em.X-ray.softdoublenullablee_EFlare[4e+32/4.7e+37]? Lower uncertainty in EFlare1e-07Jstat.error;phys.energy;em.X-ray.softdoublenullableE_EFlare[1.9e+33/7e+37]? Upper uncertainty in EFlare1e-07Jstat.error;phys.energy;em.X-ray.softdoublenullableaRise[-2.1/6.2]? Chandra soft X-ray band flare rise spectral indexspect.indexdoublenullablee_aRise[0.1/5.3]? Lower uncertainty in aRisestat.error;stat.min;spect.indexdoublenullableE_aRise[-6.2/5.8]? Upper uncertainty in aRisestat.error;stat.max;spect.indexfloatnullableaDecay[-0.45/10]? Chandra soft X-ray band flare decay spectral indexspect.indexdoublenullablee_aDecay[0.16/9.4]? Lower uncertainty in aDecaystat.error;stat.min;spect.indexdoublenullableE_aDecay[-10/8]? Upper uncertainty in aDecaystat.error;stat.max;spect.indexdoublenullableaFlare[-0.34/10]? Chandra soft X-ray band flare spectral indexspect.indexdoublenullablee_aFlare[0.1/6.7]? Lower uncertainty in aFlarestat.error;stat.min;spect.indexdoublenullableE_aFlare[-10/6]? Upper uncertainty in aFlarestat.error;stat.max;spect.indexdoublenullableaRatio[-0.8/3.6]? The alphaDecay/alphaRise ratiospect.indexdoublenullablee_aRatio[0.04/1100]? Lower uncertainty in aRatiostat.error;stat.min;spect.indexdoublenullableE_aRatio[-5400/19]? Upper uncertainty in aRatiostat.error;stat.max;spect.indexdoublenullableCSCDisplay data from the Chandra Source Catalog (CSC) 2.0 (IX/57) within 1"meta.ref.urlchar