J/ApJ/659/585ivo://CDS.VizieR/J/ApJ/659/585doi:10.26093/cds/vizier.16590585CDSHojnacki S.M.Kastner J.H.Micela G.Feigelson E.D.Lalonde S.M.2017-10-09T13:34:39Z2009-04-01T14:01:12ZCDS support team

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

cds-question@unistra.fropen-star-clustersx-ray-sourcesA large volume of low signal-to-noise, multidimensional data is available from the CCD imaging spectrometers aboard the Chandra X-Ray Observatory and the X-Ray Multimirror Mission (XMM-Newton). To make progress analyzing this data, it is essential to develop methods to sort, classify, and characterize the vast library of X-ray spectra in a nonparametric fashion (complementary to current parametric model fits). We have developed a spectral classification algorithm that handles large volumes of data and operates independently of the requirement of spectral model fits. We use proven multivariate statistical techniques including principal component analysis and an ensemble classifier consisting of agglomerative hierarchical clustering and K-means clustering applied for the first time for spectral classification. The algorithm positions the sources in a multidimensional spectral sequence and then groups the ordered sources into clusters based on their spectra. These clusters appear more distinct for sources with harder observed spectra. The apparent diversity of source spectra is reduced to a three-dimensional locus in principal component space, with spectral outliers falling outside this locus. The algorithm was applied to a sample of 444 strong sources selected from the 1616 X-ray emitting sources detected in deep Chandra imaging spectroscopy of the Orion Nebula Cluster.2007ApJ...659..585Hhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/659/585CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toJ/ApJS/160/319 : COUP: observations and source lists (Getman+, 2005)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJ/659/585https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJ/659/585http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJ/659/585https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJ/659/585https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJ/659/585http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJ/659/585GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/ApJ/659/585/table1 (Properties of the 444 COUP sources)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJ/659/585/table1?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJ/659/585/table1?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJ/659/585/table1?GETtext/xml+votable180.050000true83.6592811-5.40653390.0055555555555555566/21438 21439 22804 22805https://cdsarc.cds.unistra.fr/viz-bin/moc/J/ApJ/659/585?format=asciiX-raydefaultJ/ApJ/659/585/table1Properties of the 444 COUP sourcesrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintCOUPCOUP source number (1)meta.id;meta.mainintClass[1-17] X-ray spectral class (see paper)src.classintHR2? Hardness ratio 2 (0.5-1.7 vs. 1.7-2.8keV) (1)phot.flux;arith.ratiofloatnullableHR3Hardness ratio 3 (1.7-2.8 vs. 2.8-8.0keV) (1)phot.flux;arith.ratiofloatNHLog Hydrogen column density (1)log(cm**-2)phys.columnDensityfloatkT1Energy of first plasma component (1)keVphys.temperaturefloatkT2? Energy of second plasma component (1)keVphys.energyfloatnullableT1/T2? Ratio of first and second plasma componentsarith.factor;pos.distancefloatnullableTeff? Log of the stellar effective temperature (1)log(K)phys.temperature.effectivefloatnullableEWCa? Equivalent width of CaII line in Angstroms (1)0.1nmspect.line.eqWidthfloatnullableAV? The visual absorption (1)magphys.absorption;em.opt.VfloatnullableDelK? The {Delta}(I-K) near-infrared excess (1)magphot.color.excessfloatnullableSimbadSimbad column added by the CDSchar_RAPosition from COUP catalog (Getman et al. 2005, Cat. J/ApJS/160/319) (right ascension part)degpos.eq.ra;meta.main_DEPosition from COUP catalog (Getman et al. 2005, Cat. J/ApJS/160/319) (declination part)degpos.eq.dec;meta.main