J/AJ/98/1305ivo://CDS.VizieR/J/AJ/98/1305doi:10.26093/cds/vizier.50981305CDSMassey P.Parker J.W.Garmany C.D.2009-04-29T13:47:42Z2009-04-29T13:41:58ZCDS support team

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

cds-question@unistra.frh-ii-regionsmagellanic-cloudsnebulaeo-starswolf-rayet-starsccd-photometryspectrophotometryUsing CCD UBV photometry and spectroscopy, we have investigated the stellar content of NGC 346, the brightest H II region in the SMC. Spectra of 42 stars confirm that 33 are of O type, of which 11 are of type O6.5 or earlier; this is as many early-type O stars as is known in the rest of the SMC. From the spectroscopy and photometry we are able to construct an H-R diagram which is essentially complete down to ~10M_{sun}_. We find an initial mass-function slope {GAMMA}=-1.9, similar to that found for massive stars near the Sun and in the LMC: the presence of six stars in the mass range 40-85M_{sun}_ suggests that the upper-mass limit of the IMF is also not appreciably lower in the SMC than it is in the Galaxy. Our photometry has identified five probable red supergiants of which one was previously known. These stars, plus two B supergiants, are evolved stars of considerably lower mass (15M_{sun}_) than many of the unevolved cluster members. Most of these lower-mass, evolved stars form a spatially distinct subgroup; we believe that NGC 346 thus provides an example of sequential star formation in the SMC. We also have identified a background field population of 5M_{sun}_ stars. We find that the ionizing flux from the hot stars is consistent with the previously known Half nebular luminosity. Finally, we discuss the enigmatic W-R binary HD 5980, which our point-spread-function fitting has identified as a close visual double.1989AJ.....98.1305Mhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/AJ/98/1305CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toJ/PASP/98/1133 : The open cluster NGC 346 (Niemela+, 1986)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/AJ/98/1305https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/AJ/98/1305http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/AJ/98/1305https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/AJ/98/1305https://vizier.iucaa.in/viz-bin/votable?-source=J/AJ/98/1305http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/AJ/98/1305GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/AJ/98/1305/table2 (Photometry of NGC 346)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/AJ/98/1305/table2?https://vizier.iucaa.in/viz-bin/conesearch/J/AJ/98/1305/table2?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/AJ/98/1305/table2?GETtext/xml+votable180.050000true14.5498308-72.19343060.005555555555555556Cone search capability for table J/AJ/98/1305/table7 (Other bright stars in NGC 346)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/AJ/98/1305/table7?https://vizier.iucaa.in/viz-bin/conesearch/J/AJ/98/1305/table7?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/AJ/98/1305/table7?GETtext/xml+votable180.050000true14.677634-72.16249570.005555555555555556Cone search capability for table J/AJ/98/1305/posmk (MK types (table 6) and positions (from B. Skiff))https://vizier.cds.unistra.fr/viz-bin/conesearch/J/AJ/98/1305/posmk?https://vizier.iucaa.in/viz-bin/conesearch/J/AJ/98/1305/posmk?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/AJ/98/1305/posmk?GETtext/xml+votable180.050000true14.8832083-72.17947220.0055555555555555566/33317 33328https://cdsarc.cds.unistra.fr/viz-bin/moc/J/AJ/98/1305?format=asciiOpticaldefaultJ/AJ/98/1305/table2Photometry of NGC 346IdStar numbermeta.id;meta.mainintprimaryrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintMKindicates that the star has a MK spectral type in posmkmeta.ref.urlcharXposX positionpixpos.cartesian.x;instr.detfloatYposY positionpixpos.cartesian.y;instr.detfloatVmagV magnitudemagphot.mag;em.opt.Vfloatu_Vmag[: ] Uncertainty flag on Vmag (1)meta.code.errorcharU-BU-B colour indexmagphot.color;em.opt.U;em.opt.Bfloatu_U-B[: ] Uncertainty flag on U-B (1)meta.code.error;phot.color;em.opt.UcharB-VB-V colour indexmagphot.color;em.opt.B;em.opt.Vfloatu_B-V[: ] Uncertainty flag on B-V (1)meta.code.error;phot.color;em.opt.Bchar_RAPosition computed from (Xpos, Ypos) using the stars in file posmk.dat (right ascension part)degpos.eq.ra;meta.main_DEPosition computed from (Xpos, Ypos) using the stars in file posmk.dat (declination part)degpos.eq.dec;meta.mainJ/AJ/98/1305/table5Comparison with Niemela et al. (1986)RemRemarks (1)meta.notecharrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintIdStar numbermeta.id;meta.mainintm_IdOther star numbers when multiple starmeta.code.multipcharNameN? Niemela star number (J/PASP/98/1133)meta.idintnullableVmagV magnitude from this workmagphot.mag;em.opt.Vfloatu_Vmag[: ] Uncertainty flag on Vmagmeta.code.errorcharVmagNV magnitude from Niemela (J/PASP/98/1133)magphot.mag;em.opt.VfloatJ/AJ/98/1305/table7Other bright stars in NGC 346recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintIdStar numbermeta.id;meta.mainintRA1950Right ascension 1950pos.eq.ra;meta.mainDE1950Declination 1950pos.eq.dec;meta.mainXposX positionpixpos.cartesian.x;instr.detfloatYposY positionpixpos.cartesian.y;instr.detfloatVmagV magnitudemagphot.mag;em.opt.Vfloatu_Vmag[: ] Uncertainty flag on Vmagmeta.code.errorcharU-BU-B colour indexmagphot.color;em.opt.U;em.opt.Bfloatu_U-B[: ] Uncertainty flag on U-Bmeta.code.error;phot.color;em.opt.UcharB-VB-V colour indexmagphot.color;em.opt.B;em.opt.Vfloatu_B-V[: ] Uncertainty flag on B-Vmeta.code.error;phot.color;em.opt.BcharComComments (1)meta.notecharJ/AJ/98/1305/posmkMK types (table 6) and positions (from B. Skiff)recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintIdStar number, as in the other tablesmeta.recordintM2002? Number in Massey's Survey (II/236/smc)meta.idintnullableRAJ2000Right Ascension J2000pos.eq.ra;meta.mainDEJ2000Declination J2000pos.eq.dec;meta.mainrPos[MUz] Reference of position (1)meta.ref;poscharVmagVisual magnitude, as in table2magphot.mag;em.opt.Vfloatu_Vmag[?] Large uncertainty in Vmagmeta.code.errorcharSpTypeMK spectral type from table6src.spTypecharNotesRemarksmeta.notechar