J/ApJ/608/781ivo://CDS.VizieR/J/ApJ/608/781doi:10.26093/cds/vizier.16080781CDSDamiani F.Flaccomio E.Micela G.Sciortino S.Harnden F.R.Jr,Murray S.S.2005-08-20T15:08:26Z2005-08-20T15:08:12ZCDS support team

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

cds-question@unistra.frx-ray-sourcesopen-star-clusterspre-main-sequence-starsIn a deep 60ks Chandra ACIS X-ray observation of the very young cluster NGC 6530, we detect 884 X-ray point sources and argue that a very large fraction of them (90%-95%) must be pre-main-sequence (PMS) cluster members, mostly of low masses. This is a significant enlargement of the known NGC 6530 stellar population with respect to previous optical studies, including H{alpha} surveys. We identify 220 X-ray sources with catalogued stars down to V=17, while most unidentified sources have fainter counterparts. Moreover, we find an infrared counterpart in the 2MASS (<II/246>) catalog for 731 X-ray sources. The optically identified cluster X-ray sources are found in a band in the H-R diagram above the main sequence, in the locus of 0.5-1.5Myr PMS stars, with masses down to 0.5-1.5M_{sun}_.2004ApJ...608..781Dhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/608/781CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toII/246 : 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003)J/AJ/120/333 : UBVRI and H{alpha} in NGC 6530 (Sung+, 2000)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJ/608/781https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJ/608/781http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJ/608/781https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJ/608/781https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJ/608/781http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJ/608/781GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/ApJ/608/781/table1 (NGC 6530 X-Ray Source Properties and Identifications)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJ/608/781/table1?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJ/608/781/table1?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJ/608/781/table1?GETtext/xml+votable180.050000true270.9425833-24.42005560.0055555555555555566/28890 288918.650015785639275e-20 1.7003137259100215e-19https://cdsarc.cds.unistra.fr/viz-bin/moc/J/ApJ/608/781?format=asciiX-raydefaultJ/ApJ/608/781/table1NGC 6530 X-Ray Source Properties and IdentificationsCRateCount ratect/ksfloatrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordint[DFM2004]X-ray running numberintRAJ2000Hour of Right Ascension (J2000.0)pos.eq.ra;meta.mainDEJ2000Degree of Declination (J2000.0)pos.eq.dec;meta.maine_PosPosition errorarcsecfloate_CRateUncertainty in CRatect/ksfloatPK-SKolmogorov-Smirnov test probability X-ray source is constantfloatHR1? First hardness ratio (1)floatnullableHR2Second hardness ratio (2)floatSCB? Sung et al. (2000, Cat. <J/AJ/120/333>) number (Cl* NGC 6530 SCB NNNN in Simbad)intnullableOffX-O? X-ray and SCB optical positions offsetarcsecfloatnullableVmag? SCB V band magnitudemagfloatnullableV-I? SCB (V-I) colormagfloatnullableB-V? SCB (B-V) colormagfloatnullable2MASSThe 2MASS (Cat. <II/246>) designationcharOffX-IR? X-ray and 2MASS positions offsetarcsecfloatnullableJmag? 2MASS J band magnitudemagfloatnullableHmag? 2MASS H band magnitudemagfloatnullableKmag? 2MASS K band magnitudemagfloatnullable