J/ApJ/705/1533ivo://CDS.VizieR/J/ApJ/705/1533doi:10.26093/cds/vizier.17051533CDSChattopadhyay A.K.Chattopadhyay T.Davoust E.Mondal S.Sharina M.2017-06-28T06:58:33Z2012-01-04T08:25:16ZCDS support team

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

cds-question@unistra.frglobular-star-clustersgalaxiesvisible-astronomyastronomical-modelsAn objective classification of the globular clusters (GCs) of NGC 5128 has been carried out by using a model-based approach of cluster analysis. The set of observable parameters includes structural parameters, spectroscopically determined Lick indices and radial velocities from the literature. The optimum set of parameters for this type of analysis is selected through a modified technique of principal component analysis, which differs from the classical one in the sense that it takes into consideration the effects of outliers present in the data. Then a mixture model based approach has been used to classify the GCs into groups. The efficiency of the techniques used is tested through the comparison of the misclassification probabilities with those obtained using the K-means clustering technique. On the basis of the above classification scheme three coherent groups of GCs have been found. We propose that the clusters of one group originated in the original cluster formation event that coincided with the formation of the elliptical galaxy, and that the clusters of the two other groups are of external origin, from tidally stripped dwarf galaxies on random orbits around NGC 5128 for one group, and from an accreted spiral galaxy for the other.2009ApJ...705.1533Chttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/705/1533CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toJ/AJ/139/1871 : Kinematics of globulars in NGC 5128 (Woodley+, 2010)J/AJ/140/2101 : NGC 5128 globular clusters photometry (Sinnott+, 2010)J/ApJ/708/1335 : Spectroscopy of globulars in NGC 5128 (Woodley+, 2010)J/ApJ/682/199 : Globulars with X-ray sources in NGC 5128 (Woodley+, 2008)J/MNRAS/386/1443 : 2dF study of globular clusters in NGC 5128 (Beasley+, 2008)J/AJ/134/494 : NGC 5128 globular clusters UBVRICMT1 phot. + RV (Woodley+,J/AJ/132/2187 : MCT1 photometry of NGC 5128 GCs (Harris+, 2006)J/AJ/128/723 : Washington Photometry in NGC 5128. II (Harris+, 2004)J/AJ/128/712 : Washington Photometry in NGC 5128 (Harris+, 2004)J/ApJS/150/367 : Globular clusters in NGC 5128 (Peng+, 2004)J/A+A/369/812 : UVKs photometry of globular clusters in NGC 5128 (Rejkuba,https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJ/705/1533https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJ/705/1533http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJ/705/1533https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJ/705/1533https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJ/705/1533http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJ/705/1533GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/ApJ/705/1533/glcl (Parameters of the globular clusters of NGC 5128 used in Principal Component Analysis (PCA) and Cluster Analysis (CA) and derived parameters)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJ/705/1533/glcl?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJ/705/1533/glcl?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJ/705/1533/glcl?GETtext/xml+votable180.050000true201.2335833-43.17122220.0055555555555555566/432622.9196443747461696e-19 3.2860540898823595e-19https://cdsarc.cds.unistra.fr/viz-bin/moc/J/ApJ/705/1533?format=asciiOpticaldefaultJ/ApJ/705/1533/glclParameters of the globular clusters of NGC 5128 used in Principal Component Analysis (PCA) and Cluster Analysis (CA) and derived parametersrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintNameGlobular cluster name (G1)meta.id;meta.maincharf_Name[a] discarded in CA (G2)meta.codecharGroup[1,3]? Group membership found by CA (G3)meta.idintnullablecConcentration (c~log(R_tid_/R_c_)) (G1)meta.notefloatmuVV surface brightness averaged over half-light radius (<{mu}_v_>_h_) (G1)mag.arcsec**-2phot.mag.sb;em.opt.Vfloatmu0Extinction-corrected central surface brightness in the F606W bandpass (G1)mag.arcsec**-2phot.mag.sb;em.opt.RfloatW0Dimensionless central potential of the best-fitting model (G1)stat.fit.paramfloatlogRcLog core radius (G1)log(pc)phys.size.radiusfloatlogRtidLog tidal radius (G1)log(pc)phys.size.radiusfloatlogrhLog half-light radius (G1)log(pc)phys.size.radiusfloatlogMIntegrated model mass (logM_tot_) (G1)log(solMass)phys.mass;meta.modelledfloatrho0Central volume density (G1)solMass.pc**-3meta.bib.volumedoublesig.PPredicted line of sight velocity dispersion at the cluster center ({sigma}_p,0_) (G1)km/sphys.veloc.dispersionfloattrhTwo-body relaxation time at the model projected half-mass radius (G1)1e+09yrtime.relaxfloatRgcGalactocentric radius (G1)kpcphys.size.radius;pos.galactocentricfloatT1Washington T1 magnitude (G1)magphot.mag;em.opt.Rfloat[Fe/H]Fe/H abundance (G1)log(Sun)phys.abund.Fefloat(C-T1)0Extinction corrected (C-T1)_0_ color index (G1)magphot.color;em.opt.U;em.opt.RfloatRV? Weighted mean radial velocity from Woodley et al. (2007, Cat. J/AJ/134/494)km/sphys.veloc;pos.heliocentricintnullable[Z/H]? Metallicitylog(Sun)phys.abund.Zfloatnullableu_[Z/H][:] Uncertainty flag on [Z/H] (1)meta.notechare_[Z/H]? [Z/H] uncertaintylog(Sun)stat.error;src.redshiftfloatnullableAge? AgeGyrtime.agefloatnullableu_Age[:] Uncertainty flag on Age (1)meta.code.error;time.agechare_Age? Age uncertaintyGyrstat.error;time.agefloatnullableVrot? Rotational velocitykm/sphys.veloc.rotatfloatnullablesigma? Velocity dispersion ({sigma}_V_)km/sphys.veloc.dispersionfloatnullableXmIndicates number of cross-matches within 1.5" with other NGC 5128 globular clusters catalogs (Woodley+ 2007 and 2010 and Harris+ 2006)meta.noteintnullableSimbadNameSimbad column added by the CDSmeta.idchar_RAPositions from Simbad (right ascension part)degpos.eq.ra;meta.main_DEPositions from Simbad (declination part)degpos.eq.dec;meta.main