J/ApJ/567/423ivo://CDS.VizieR/J/ApJ/567/423doi:10.26093/cds/vizier.15670423CDSKohno M.Koyama K.Hamaguchi K.2003-04-25T20:10:28Z2003-04-25T20:09:43ZCDS support team

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

cds-question@unistra.frpre-main-sequence-starsx-ray-sourcesWe observed the Monoceros R2 molecular cloud with the ACIS-I array on board the Chandra X-Ray Observatory. From the central 3.2'x3.2' region, we detect 154 sources above the detection limit of ~5x10^-16^erg/s/cm^2^ with a 100ks exposure. About 85% of the X-ray sources are identified with an infrared counterpart, including four high-mass stars in the zero-age main-sequence (ZAMS) and/or premain-sequence (PMS) phase. The X-ray spectra of the high-mass ZAMS and PMS stars are represented by a thin thermal plasma model of a temperature above ~2keV. The X-rays are time variable and exhibit rapid flares. This high-temperature plasma and flaring activity is similar to that seen in low-mass PMS stars and is contrary to the behavior observed in high-mass main-sequence stars.The X-ray luminosity increases as the intrinsic K-band flux increases. However, the X-ray luminosity saturates at a level of ~10^31^erg/s. We conclude that high-mass ZAMS and PMS stars emit X-rays, possibly because of magnetic activity such as that of low-mass stars.2002ApJ...567..423Khttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/567/423CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toJ/AJ/114/198 : The Monoceros R2 Cluster (Carpenter+ 1997)J/ApJ/566/974 : CHANDRA obs. of YSOs in OMC-2 and OMC-3 (Tsujimoto+, 2002)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJ/567/423https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJ/567/423http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJ/567/423https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJ/567/423https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJ/567/423http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJ/567/423GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/ApJ/567/423/table1 (CHANDRA X-ray sources in the Monoceros R2 region)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJ/567/423/table1?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJ/567/423/table1?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJ/567/423/table1?GETtext/xml+votable180.050000true91.918875-6.37936110.0055555555555555566/21458https://cdsarc.cds.unistra.fr/viz-bin/moc/J/ApJ/567/423?format=asciiX-raydefaultJ/ApJ/567/423/table1CHANDRA X-ray sources in the Monoceros R2 regionrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordint[KKH2002]Source numbermeta.id;meta.mainintRAJ2000Hour of Right Ascension (J2000) (1)pos.eq.ra;meta.mainDEJ2000Degree of Declination (J2000) (1)pos.eq.dec;meta.mainCtsCHANDRA countsctphot.count;em.X-rayintVarPrVariable probability (2)%stat.fit.goodnessfloatTemp? TemperaturekTphys.temperaturefloatnullablel_TempLimit flag on the 90% confidence limitmeta.code.errorchare_Temp? The 90% confidence value on Temp or lower limit if E_Temp is givenkTstat.errorfloatnullableE_Temp? The upper 90% confidence limit on TempkTstat.errorfloatnullablef_Temp[fg] Flag on Temp (3)meta.code.errorcharLogEMLog of the emission measurelog(cm**-3)phys.emissMeasurefloate_LogEMThe lower 90% confidence limit on LogEMlog(cm**-3)stat.errorfloatE_LogEMThe upper 90% confidence limit on LogEMlog(cm**-3)stat.errorfloatNHHydrogen column density1e+22cm**-2phys.columnDensityfloate_NHThe lower 90% confidence limit on NH1e+22cm**-2stat.errorfloatE_NHThe upper 90% confidence limit on NH1e+22cm**-2stat.errorfloatFluxObserved 0.5-10.0 keV band flux in 10^-15^erg/cm^2^/s1e-15mW.m**-2phot.flux;em.X-rayfloatLogLXLog of the absorption-corrected 0.5-10.0keV band luminosity in erg/slog(1e-07W)phys.luminosityfloate_LogLXThe lower 90% confidence limit on LogLXlog(1e-07W)stat.errorfloatE_LogLXThe upper 90% confidence limit on LogLXlog(1e-07W)stat.errorfloatIRNum? IR counterpart number (4)meta.id.crossintnullableIRNameIR source name (5)meta.id.crosschar