J/A+A/618/A15ivo://CDS.VizieR/J/A+A/618/A15doi:10.26093/cds/vizier.36180015CDSLatour M.Randall S.K.Calamida A.Geier S.Moehler S.2019-12-23T08:37:35Z2018-10-05T08:01:51ZCDS support team

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

cds-question@unistra.frglobular-star-clustershorizontal-branch-starssubdwarf-starsradial-velocityspectroscopyThe presence of extreme horizontal branch (EHB) and blue hook stars in some Galactic globular clusters (GGCs) constitutes one of the remaining mysteries of stellar evolution. While several evolutionary scenarios have been proposed to explain the characteristics of this peculiar population of evolved stars, their observational verification has been limited by the availability of spectroscopic data for a statistically significant sample of such objects in any single GGC. In this first paper, we focus on {omega} Centauri, a peculiar, massive GGC that hosts multiple stellar populations. We use non-LTE model atmospheres to derive atmospheric parameters (Teff, log g and N(He)/N(H)) and spectroscopic masses for 152 EHB stars in the cluster. We also search for close binaries among these stars based on radial velocity variations. The majority of our sample consists of sdOB stars that have roughly solar or super-solar atmospheric helium abundances. It is these objects that constitute the blue hook at V>18.5mag in the {omega} Cen colour-magnitude diagram.2018A&A...618A..15Lhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/618/A15CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toJ/A+A/526/A136 : Hot HB stars in {omega} Cen (Moehler+, 2011)J/A+A/547/A109 : Parameters of HB stars in {omega} Cen (Moni Bidin+, 2012)J/A+A/589/A1 : Extreme Horizontal Branch stars in {omega} Cen (Randall+ 2016)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/618/A15https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/618/A15http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/618/A15https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/618/A15https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/618/A15http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/618/A15GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/A+A/618/A15/tableb3 (Spectroscopic EHB stars in {omega} Cen)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/618/A15/tableb3?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/618/A15/tableb3?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/618/A15/tableb3?GETtext/xml+votable180.050000true201.76322694-47.542901110.0055555555555555566/43225 432272.8871749643927257e-19 4.826256797203527e-19https://cdsarc.cds.unistra.fr/viz-bin/moc/J/A+A/618/A15?format=asciidefaultJ/A+A/618/A15/tableb3Spectroscopic EHB stars in {omega} CenrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintIDStar identification number (1)meta.id;meta.mainintRAJ2000Right ascension (J2000)degpos.eq.ra;meta.mainDEJ2000Declination (J2000)degpos.eq.dec;meta.mainTeff[23463/61960] Effective temperatureKphys.temperature.effectiveinte_TeffError on the effective temperature (2)Kstat.error;phys.temperature.effectiveintlogg[4.75/6.36] Surface gravity in loglog(cm.s**-2)phys.gravityfloate_loggError on the surface gravity (2)log(cm.s**-2)stat.errorfloatlogN(He)/N(H)[-4.09/1.17] Surface helium abundancelog(Sun)phys.abund.Yfloate_logN(He)/N(H)Error on surface helium abundance (2)log(Sun)stat.errorfloatUmag? WFI magnitude in U filter (1)magphot.mag;em.opt.UfloatnullableBmagWFI magnitude in B filter (1)magphot.mag;em.opt.BfloatVmagWFI magnitude in V filter (1)magphot.mag;em.opt.VfloatImagWFI magnitude in I filter (1)magphot.mag;em.opt.IfloatF435W? ACS magnitude in F435W filter (1)magphot.mag;em.opt.BfloatnullableF625W? ACS magnitude in F625W filter (1)magphot.mag;em.opt.RfloatnullableRV[164/308] Radial velocitykm/sphys.veloc;pos.heliocentricinte_RV? Error on the radial velocitykm/sstat.errorintnullables_RV? Standard deviation on the radial velocity in cases of radial velocities averaged from different sourceskm/sstat.stdev;spect.dopplerVelocfloatnullableMassSpectroscopic masssolMassphys.massfloate_MassError on the spectroscopic masssolMassstat.error;phys.massfloatE(B-V)Estimated color excessmagphot.color.excessfloatMbcSpectroscopic mass derived using a bolometric correctionsolMassphys.massfloatID1? ID from Moehler et al. (2011, Cat. J/A+A/526/A136)meta.idintnullableID2? ID from Moni Bidin et al. (2012, Cat. J/A+A/547/A109)meta.idintnullableSampleSpectroscopic sample (3)pos.parallax.spectcharSimbadSimbad column added by the CDSmeta.ref.urlchar