J/A+A/645/A42ivo://CDS.VizieR/J/A+A/645/A42doi:10.26093/cds/vizier.36450042CDSIlin E.Schmidt S.J.Poppenhager K.Davenport J.R.A.Kristiansen M.H.,Omohundro M.2021-09-10T07:30:04Z2021-01-07T06:56:46ZCDS support team

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

cds-question@unistra.fropen-star-clustersdwarf-starsvariable-starsvisible-astronomyphotographic-photometryeffective-temperatureMagnetic fields are a key component in the main sequence evolution of low mass stars. Flares, energetic eruptions on the surfaces of stars, are an unmistakable manifestation of magnetically driven emission. The occurrence rates and energy distributions of flares trace stellar characteristics such as mass and age. But before flares can be used to constrain stellar properties, the flaring-age-mass relation requires proper calibration. This work sets out to quantify flaring activity of independently age-dated main sequence stars for a broad range of spectral types using optical light curves obtained by the Kepler satellite. Drawing from the complete K2 archive, we searched 3435 80 day long light curves of 2111 open cluster members for flares using the open-source software packages K2SC to remove instrumental and astrophysical variability from K2 light curves, and AltaiPony to search and characterize the flare candidates. We confirmed a total of 3844 flares on high probability open cluster members with ages from zero age main sequence (Pleiades) to 3.6Gyr (M67). We extended the mass range probed in the first study of this series to span from Sun-like stars to mid-M dwarfs. We added the Hyades (690Myr) to the sample as a comparison cluster to Praesepe (750Myr), the 2.6Gyr old Ruprecht 147, and several hundred light curves from the late K2 Campaigns in the remaining clusters. We found that the flare energy distribution was similar in the entire parameter space, following a power law relation with an exponent between 1.84 and 2.39. We confirmed that flaring rates declined with age, and declined faster for higher mass stars. Our results are in good agreement with most previous statistical flare studies. We found evidence that a rapid decline in flaring activity occurred in M1-M2 dwarfs around Hyades/Praesepe age, when these stars spun down to rotation periods of about 10 d, while higher mass stars had already transitioned to lower flaring rates, and lower mass stars still resided in the saturated activity regime. We conclude that some discrepancies between our results and flare studies that used rotation periods for their age estimates could be explained by sample selection bias toward more active stars, but others may hint at limitations of using rotation as an age indicator without additional constraints from stellar activity.2021A&A...645A..42Ihttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/645/A42CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toJ/A+A/622/A133 : M45, M44 and M67 flare stars (Ilin+, 2019)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/645/A42https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/645/A42http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/645/A42https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/645/A42https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/645/A42http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/645/A42GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/A+A/645/A42/stars (Stellar parameters)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/645/A42/stars?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/645/A42/stars?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/645/A42/stars?GETtext/xml+votable180.050000true56.23524.43260.0055555555555555564/28 293 5/91 94 101 116-118 120 1170-1171 1177 1179-1181 1218 5887 6050 6058 6/260 272 276 313 315 322 330 335 337 339-342 349 351 353 355 357-361 363 368 370-371 375 380-381 383 409 413 415 437 439 476-478 484-486 496 1025 1029 1031-1032 1035-1036 1041-1042 1044 1046-1047 1049-1050 1052 1056 1058 1061 1064-1065 1090 1094 1096-1097 4253 4255 4296 4298-4299 4320 4331 4334-4335 4344 4346-4347 4351 4637 4639 4659 4661 4673 4675 4677-4679 4704-4705 4707 4712-4713 4728-4730 4732-4734 4800 4805 4816-4818 4866 4896 23479 23505 23508 23510 23515 23518-23519 23523 23526 23529 23531-23533 23536-23537 23539-23540 23542 23547 24103-24106 24110 24114 24192 24194 24196 24204 24206-24207 24210 24216 24224-24225 24230 24236-24238 24241-24242 24248 24251 24256 24297-24298 29044-29045 29047 29728 29730https://cdsarc.cds.unistra.fr/viz-bin/moc/J/A+A/645/A42?format=asciiOpticaldefaultJ/A+A/645/A42/starsStellar parametersIDEPIC IDmeta.id;meta.mainlongprimaryrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintFlaresindicates flares data in table flares.datmeta.ref.urlcharCampaignK2 observing campaignmeta.id;obsintRAJ2000Right Ascension (J2000)degpos.eq.ra;meta.mainDEJ2000Declination (J2000)degpos.eq.dec;meta.mainPmemb[0.8/1.0] Mean membership probability (1)stat.probability;stat.meanfloatTeff[2780/5997] Stellar effective temperatureKphys.temperature.effectiveinte_TeffUncertainty on effective temperatureKstat.error;phys.temperature.effectiveintR[0.13/1.15] stellar radiussolRadphys.size.radiusfloate_RUncertainty on stellar radiussolRadstat.errorfloatLbolProjected stellar bolometric luminosity1e-07Wphys.luminositydoublee_LbolUncertainty on projected stellar bolometric luminosity1e-07Wstat.errordoubleLKeplerProjected stellar luminosity in the Kepler band1e-07Wphys.luminositydoublee_LKeplerUncertainty on projected stellar luminosity in the Kepler band1e-07Wstat.errordoubleSimbadSimbad column added by the CDSmeta.ref.urlcharJ/A+A/645/A42/flaresStellar flares law fit parameters (table 2)recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintIDEPIC IDmeta.id;meta.mainlongCampaignK2 observing campaignmeta.id;obsintcstartFlare start cadence numbermeta.idintcstopFlare end cadence numbermeta.idinttstartFlare start time, Barycentric Kepler Julian Datedtime.startdoubletstopFlare stop time, Barycentric Kepler Julian Datedtime.enddoubleED[1.82/82185] Measured equivalent durationstime.durationdoublee_EDUncertainty on EDsstat.errorfloatAmpl-rec[0.0003/9.6748] Measured relative flare amplitudesrc.var.amplitudefloatNoteNote saturation of the detectormeta.notechardtpNumber of accepted data points in light curvemeta.numberintLKeplerStellar luminosity in the Kepler band1e-07Wphys.luminositydoublee_LKeplerUncertainty on Lum_Kepler1e-07Wstat.errordoubleTeff-med[2780/5996] Effective temperatureKphys.temperature.effectiveinte_Teff-medUncertainty on Teff-medKstat.errorintLbolStellar bolometric luminosity1e-07Wphys.luminositydoublee_LbolUncertainty on bolometric luminosity1e-07Wstat.errordoubleClusterOpen cluster namemeta.id.parentcharJ/A+A/645/A42/ffdsFlare frequency distributions and power law fit parameters (table 3)recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintTeffmin[2500/5000] Minimum effective temperature in binKphys.temperature.effective;stat.minintTeffmax[3000/6000] Maximum effective temperature in binKphys.temperature.effective;stat.maxintClusterOpen cluster namemeta.id.parentcharalpha[1.84/2.31] FFD power law index in ED space (1)spect.indexfloatE_alphaUpper uncertainty on alpha (1)stat.error;stat.maxfloate_alphaLower uncertainty on alpha (1)stat.error;pos.eq.rafloatbeta[0.85/4707.79] FFD intercept in ED space (1)s**-1spect.indexfloatE_betaUpper uncertainty on beta (1)s**-1stat.error;stat.maxdoublee_betaLower uncertainty on beta (1)s**-1stat.errorfloatNflares[1/970] Number of flares in binmeta.numberintNfit[1/612] Number of flares used in FFD fitmeta.numberintAge[135/3639] Open cluster age (2)Myrtime.ageintE_AgeUpper uncertainty on open cluster ageMyrstat.error;stat.maxinte_AgeUpper uncertainty on open cluster ageMyrstat.error;time.ageintEDmin[9.9/1236] Minimum equivalent duration used in fitstime.intervalfloatEDmax[59/82185] Maximum equivalent duration used in fitstime.intervaldoublealpha-en[1.86/2.39] FFD power law index in energy space (1)spect.indexfloatE_alpha-enUpper uncertainty on alpha-en (1)stat.error;stat.maxfloate_alpha-enLower uncertainty on alpha-en (1)stat.errorfloatbeta-en[1.28E+28/4.44E+45] FFD intercept in energy space (1)s**-1spect.indexdoubleE_beta-enUpper uncertainty on beta_en (1)s**-1stat.error;stat.maxdoublee_beta-enLower uncertainty on beta_en (1)s**-1stat.errordoubleNflares-en[1/970] Number of flares in bin (energy space)meta.numberintNfit-en[1/663] Number of flares used in FFD fit (energy space)meta.numberintalphaD[1.47/2.18] FFD power law index from Davenport et al., 2019ApJ...871..241Dspect.indexfloatbetaD[7.29E+16/9.24E+39] FFD intercept from Davenport et al., 2019ApJ...871..241Ds**-1spect.indexdoubleEKpmin[9.01E+31/6.25E+33] Minimum energy used in fit1e-07Jphys.energydoubleEKpmax[3.80E+32/3.01E+35] Maximum energy used in fit1e-07Jphys.energydouble