J/A+A/463/981ivo://CDS.VizieR/J/A+A/463/981doi:10.26093/cds/vizier.34630981CDSRauw G.Manfroid J.Gosset E.Naze Y.Sana H.De Becker M.Foellmi C.,Moffat A.F.J.2017-06-19T07:57:28Z2007-06-17T08:28:54ZCDS support team

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

cds-question@unistra.fropen-star-clustersccd-photometryvisible-astronomybroad-band-photometryThe properties of the early-type stars in the core of the Westerlund 2 cluster are examined in order to establish a link between the cluster and the very massive Wolf-Rayet binary WR20a as well as the H II complex RCW 49. Photometric monitoring as well as spectroscopic observations of Westerlund 2 are used to search for light variability and to establish the spectral types of the early-type stars in the cluster core. The first light curves of the eclipsing binary WR 20a in B and V filters are analysed and a distance of 8kpc is inferred. Three additional eclipsing binaries, which are probable late O or early B-type cluster members, are discovered, but none of the known early O-type stars in the cluster displays significant photometric variability above 1% at the 1-sigma level. The twelve brightest O-type stars are found to have spectral types between O3 and O6.5, significantly earlier than previously thought. The distance of the early-type stars in Westerlund 2 is established to be in excellent agreement with the distance of WR20a, indicating that WR20a actually belongs to the cluster. Our best estimate of the cluster distance thus amounts to 8.0+/-1.4kpc. Despite the earlier spectral types, the currently known population of early-type stars in Westerlund 2 does not provide enough ionizing photons to account for the radio emission of the RCW 49 complex. This suggests that there might still exist a number of embedded early O-stars in RCW49.2007A&A...463..981Rhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/463/981CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toJ/A+AS/127/423 : VI photometry of Westerlund 1 and 2 (Piatti+ 1998)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/463/981https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/463/981http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/463/981https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/463/981https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/463/981http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/463/981GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/A+A/463/981/table4 (BV mean photometry of 1073 stars in the field of view around Westerlund 2)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/463/981/table4?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/463/981/table4?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/463/981/table4?GETtext/xml+votable180.050000true156.01-57.7431110.0055555555555555566/37343 38026https://cdsarc.cds.unistra.fr/viz-bin/moc/J/A+A/463/981?format=asciiOpticaldefaultJ/A+A/463/981/table23B and V photometric time series of WR20a and 3 eclipsing binaries in Westerlund 2recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintNameObject name (WR20a, MSP223, MSP096 or MSP044) (1)meta.id;meta.maincharJDJulian Daydtime.epochdoubleFilter[BV] Filter Name (either Johnson B or V)meta.id;instr.filtercharsec(z)Airmass at the time of observationobs.airMassfloatmagB or V magnitudemagphot.magfloate_magUncertainty on the magnitudemagstat.error;phot.magfloatSeeingSeeing (FWHM) in pixels (1pix=0.37arcsec)pixinstr.obsty.seeingfloatJ/A+A/463/981/table4BV mean photometry of 1073 stars in the field of view around Westerlund 2recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintRAJ2000Right Ascension J2000pos.eq.ra;meta.mainDEJ2000Declination J2000pos.eq.dec;meta.mainVmagMean observed Johnson V magnitudemagphot.mag;em.opt.Vfloate_VmagUncertainty on the V magnitudemagstat.error;phot.mag;em.opt.VfloatB-VMean observed Johnson B-V colourmagphot.color;em.opt.B;em.opt.Vfloate_B-VUncertainty on the B-V colourmagstat.error;phot.color;em.opt.Bfloat