J/ApJ/910/25ivo://CDS.VizieR/J/ApJ/910/25doi:10.26093/cds/vizier.19100025CDSSasaki R.Tsuboi Y.Iwakiri W.Nakahira S.Maeda Y.Gendreau K.,Corcoran M.F.Hamaguchi K.Arzoumanian Z.Markwardt C.B.Enoto T.,Sato T.Kawai H.Mihara T.Shidatsu M.Negoro H.Serino M.2022-10-14T13:50:02Z2022-09-14T13:35:41ZCDS support team

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

cds-question@unistra.frstellar-flaresx-ray-sourcesspectroscopic-binary-starsvariable-starsmultiple-starsWe report that the RS CVn-type star GT Mus (HR 4492, HD101379+HD101380) was the most active star in the X-ray sky in the last decade in terms of the scale of recurrent energetic flares. We detected 11 flares from GT Mus in 8yr of observations with the Monitor of All-sky X-ray Image (MAXI) from 2009 August to 2017 August. The detected flare peak luminosities were 1-4x10^33^erg/s in the 2.0-20.0keV band for its distance of 109.6pc. Our timing analysis showed long durations ({tau}_r_+{tau}_d_) of 2-6d with long decay times ({tau}_d_) of 1-4d. The released energies during the decay phases of the flares in the 0.1-100keV band were in the range of 1-11x10^38^erg, which are at the upper end of the observed stellar flare. The released energies during the whole duration were in the range of 2-13x10^38^erg in the same band. We carried out X-ray follow-up observations for one of the 11 flares with the Neutron star Interior Composition Explorer (NICER) on 2017 July 18 and found that the flare cooled quasi-statically. On the basis of a quasi-static cooling model, the flare loop length is derived to be 4x10^12^cm (or 60R_{sun}_). The electron density is derived to be 1x10^10^cm^-3^, which is consistent with the typical value of solar and stellar flares (10^10-13^cm^-3^). The ratio of the cooling timescales between radiative ({tau}_rad_) and conductive ({tau}_cond_) cooling is estimated to be {tau}_rad_~0.1{tau}_cond_ from the temperature; thus, radiative cooling was dominant in this flare.2021ApJ...910...25Shttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/910/25CatalogResearchIsServedByTAP VizieR generic servicerelated-toIX/10 : ROSAT All-Sky Bright Source Catalogue (1RXS) (Voges+ 1999)I/337 : Gaia DR1 (Gaia Collaboration, 2016)I/345 : Gaia DR2 (Gaia Collaboration, 2018)V/76 : Chromospherically Active Binaries (Strassmeier+ 1993)J/A+A/394/505 : UBV photometry of LQ Hya (Berdyugina+, 2002)J/AJ/129/2798 : AR Mon photometry and radial velocities (Williamon+, 2005)J/MNRAS/389/925 : Triple and quadruple stars (Tokovinin, 2008)J/A+A/521/A36 : BV differential photometry of V711 Tau (Muneer+, 2010)J/ApJ/743/48 : Stars with rot. periods & X-ray luminosities (Wright+, 2011)J/A+A/559/A97 : II Pegasus photometry during 1979-2010 (Lindborg+, 2013)J/A+A/614/A125 : Stellar content of the XMM-Newton slew survey (Freund+, 2018)http://maxi.riken.jp/mxondem/ : MAXI on-demand processhttps://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJ/910/25https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJ/910/25http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJ/910/25https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJ/910/25https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJ/910/25http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJ/910/25GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapX-raydefaultJ/ApJ/910/25/table1Flare epoch, photon flux, and significance of detection with MAXIDateDate of observation (UT) (3)stime.epochnullablerecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintIDFlare identifier (FN01 to FN11)meta.id;meta.maincharr_IDFlag on ID (1)meta.ref;pos.framecharMJD[55073.69/57952.52] Modified Julian Date (2)dtime.epochdoublee_MJD[0.39/1.42] MJD uncertaintydstat.error;time.epochfloatFlux[0.07/0.27] 2-10keV flux in photons/s/cm^2^ unitsph.s**-1.cm**-2phot.flux;em.X-rayfloate_Flux[0.01/0.02] Flux uncertaintyph.s**-1.cm**-2stat.error;phot.fluxfloatSig[6/25.3] Significance in {sigma}stat.fit.goodnessfloatDetDetection method (4)meta.codecharLCInteractive LC Plotmeta.ref.urlcharJ/ApJ/910/25/fig2Light curves of the eleven flares of GT Mus detected with MAXI in the 2.0-10.0keV bandrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintIDFlare identifier (FN01 to FN11)meta.id;meta.maincharMJDr[-5.9/10] Relative time in MJD (1)dtime;arith.difffloate_MJDr[0.001/0.25] Uncertainty in MJDrdstat.errorfloatFlux[-0.027/0.31] MAXI 2-10keV band Photon fluxph.s**-1.cm**-2phot.flux;em.X-ray.mediumfloate_Flux[0.006/0.05] Uncertainty in Fluxph.s**-1.cm**-2stat.error;phot.fluxfloat