J/AJ/145/46ivo://CDS.VizieR/J/AJ/145/46doi:10.26093/cds/vizier.51450046CDSLim B.Chun M.-Y.Sung H.Park B.-G.Lee J.-J.Sohn S.T.Hur H.,Bessell M.S.2026-01-13T18:42:32Z2014-03-26T06:28:15ZCDS support team

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

cds-question@unistra.frx-ray-sourcesopen-star-clustersinfrared-photometryvisible-astronomybroad-band-photometrystellar-spectral-typesWesterlund 1 is the most important starburst cluster in the Galaxy due to its massive star content. We have performed BVI_C_ and JK_S_ photometry to investigate the initial mass function (IMF). By comparing the observed color with the spectral-type-intrinsic-color relation, we obtain the mean interstellar reddening of <E(B-V)>=4.19+/-0.23 and <E(J-K_S_)>=1.70+/-0.21. Due to the heavy extinction toward the cluster, the zero-age main sequence fitting method based on optical photometry proved to be inappropriate for the distance determination, while the near-infrared photometry gave a reliable distance to the cluster, 3.8kpc from the empirical relation. Using the recent theoretical stellar evolution models with rotation, the age of the cluster is estimated to be 5.0+/-1.0Myr. We derived the IMF in the massive part and obtained a fairly shallow slope of {Gamma}=-0.8+/-0.1. The integration of the IMF gave a total mass for the cluster in excess of 5.0x10^4^M_{sun}_. The IMF shows a clear radial variation indicating the presence of mass segregation. We also discuss the possible star formation history of Westerlund 1 from the presence of red supergiants and relatively low luminosity yellow hypergiants.2013AJ....145...46Lhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/AJ/145/46CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toB/ocl : Optically visible open clusters and Candidates (Dias+ 2002-2013)VII/233 : The 2MASS Extended sources (IPAC/UMass, 2003-2006)II/221 : The LF Survey (McCuskey+ 1949-1959)J/A+A/477/147 : X-ray sources in Westerlund 1 (Clark+, 2008)J/AJ/135/441 : VRIH{alpha} photometry in NGC 2264 (Sung+, 2008)J/AJ/133/2696 : BVRI light curves of Westerlund 1 stars (Bonanos, 2007)J/ApJ/646/269 : Multiwavelength analysis of NGC 2362 (Delgado+, 2006)J/AJ/127/1014 : CCD UBVRIHa photometry in NGC 3603 (Sung+, 2004)J/AJ/120/333 : UBVRI and H{alpha} in NGC 6530 (Sung+, 2000)J/MNRAS/310/982 : UBVI CCD Photometry of M11 - II. (Sung+ 1999)J/MNRAS/306/361 : UBVI CCD photometry of M35 (NGC 2168) (Sung+ 1999)J/A+AS/127/423 : VI photometry of Westerlund 1 and 2 (Piatti+ 1998)J/AJ/115/734 : NGC 6231 UBVRI and H{alpha} photometry (Sung+ 1998)J/AJ/114/2644 : UBVRIHa photometry of NGC2264 (Sung+, 1997)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/AJ/145/46https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/AJ/145/46http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/AJ/145/46https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/AJ/145/46https://vizier.iucaa.in/viz-bin/votable?-source=J/AJ/145/46http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/AJ/145/46GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/AJ/145/46/table4 (Photometric data in Westerlund 1)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/AJ/145/46/table4?https://vizier.iucaa.in/viz-bin/conesearch/J/AJ/145/46/table4?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/AJ/145/46/table4?GETtext/xml+votable180.050000true251.5794583-45.786750.0055555555555555566/42206-42207 42228-422292.367228618189496e-19 3.852589004194616e-19https://cdsarc.cds.unistra.fr/viz-bin/moc/J/AJ/145/46?format=asciiX-rayOpticalInfrareddefaultJ/AJ/145/46/table4Photometric data in Westerlund 1recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintStar[-8/27521] Star running number <[LCS2013] NNNNN> in Simbad (1)meta.id;meta.mainintRAJ2000Hour of Right Ascension (J2000)pos.eq.ra;meta.mainindexedDEJ2000Degree of Declination (J2000)pos.eq.dec;meta.maino_VmagNumber of Vmag observationsmeta.numberintVmag[14.88/24.271]? The V-band (Harris) magnitudemagphot.mag;em.opt.Vfloatnullablee_Vmag? Uncertainty in Vmagmagstat.error;phot.magfloatnullableo_ImagNumber of Imag observationsmeta.numberintImag[9.776/22.564]? The Ic band (Harris) magnitudemagphot.mag;em.opt.Ifloatnullablee_Imag? Uncertainty in Imagmagstat.error;phot.magfloatnullableo_V-INumber of V-I observationsmeta.numberintV-I[0.191/8.378]? The (V-Ic) color indexmagphot.color;em.opt.V;em.opt.Ifloatnullablee_V-I? Uncertainty in V-Imagstat.error;phot.color;em.opt.Vfloatnullableo_B-VNumber of B-V observationsmeta.numberintB-V[0.077/5.053]? The (B-V) color indexmagphot.color;em.opt.B;em.opt.Vfloatnullablee_B-V? Uncertainty in B-Vmagstat.error;phot.color;em.opt.Bfloatnullableo_U-BNumber of U-B observationsmeta.numberintU-B[-8.03/1.737]? The (U-B) color indexmagphot.color;em.opt.U;em.opt.Bfloatnullablee_U-B? Uncertainty in U-Bmagstat.error;phot.color;em.opt.Ufloatnullable2MASSThe 2MASS identifier (HHMMSSss+DDMMSSs, J2000)meta.idcharX[X] X=X-ray emission starmeta.codecharSpTMK Spectral type (2)src.spTypechar2MDisplay the 2MASS data (Cutri et al. 2003, Cat. II/246)meta.ref.urlchar