J/A+A/573/A92ivo://CDS.VizieR/J/A+A/573/A92doi:10.26093/cds/vizier.35730092CDSGratton R.G.Lucatello S.Sollima A.Carretta E.Bragaglia A.,Momany Y.D'Orazi V.Salaris M.Cassisi S.Stetson P.B.2017-06-23T14:20:38Z2015-03-11T14:36:12ZCDS support team

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

cds-question@unistra.frgalaxiesglobular-star-clustershorizontal-branch-starschemical-abundancesphotometryWe used FLAMES+GIRAFFE (Medusa mode) at the VLT to obtain moderately high resolution spectra for 30 red horizontal branch (RHB) stars, 4 RR Lyrae variables, and 17 blue horizontal branch (BHB) stars in the low-concentration, moderately metal-rich globular cluster NGC 6723 ([Fe/H]=-1.22+/-0.08 from our present sample). The spectra were optimized to derive O and Na abundances. In addition, we obtained abundances for other elements, including N, Fe, Mg, Ca, Ni, and Ba. We used these data to discuss the evidence of a connection between the distribution of stars along the horizontal branch (HB) and the multiple populations that are typically present in globular clusters. We found that all RHB and most (13 out of 17) BHB stars are O-rich, Na-poor, and N-poor; these stars probably belong to the first stellar generation in this cluster. Only the four warmest observed stars are (moderately) O-poor, Na-rich, and N-rich, and they probably belong to the second generation. While our sample is not fully representative of the whole HB population in NGC 6723, our data suggest that in this cluster only HB stars warmer than ~9000K, that is one fourth of the total, belong to the second generation, if at all. Since in many other clusters this fraction is about two thirds, we conclude that the fraction of first/second generation in globular clusters may be strongly variable. In addition, the wide range in colour of chemically homogeneous first-generation HB stars requires a considerable spread in mass loss (>0.10M_{sun}_). The reason for this spread is yet to be understood. Finally, we found a high Ba abundance, with a statistically significant radial abundance gradient.2015A&A...573A..92Ghttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/573/A92CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toJ/A+A/534/A123 : Horizontal branch stars in NGC 2808 (Gratton+, 2011)J/A+A/539/A19 : Horizontal branch stars in NGC 1851 (Gratton+, 2012)J/A+A/549/A41 : Horizontal branch stars in 47 Tuc and M5 (Gratton+, 2013)J/A+A/563/A13 : Horizontal branch stars in M22 (Gratton+, 2014)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/573/A92https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/573/A92http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/573/A92https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/573/A92https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/573/A92http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/573/A92GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/A+A/573/A92/stars (Photometric (table 2) and spectroscopic (table3) data, and atmospheric parameters (table5))https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/573/A92/stars?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/573/A92/stars?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/573/A92/stars?GETtext/xml+votable180.050000true284.82925-36.674560.0055555555555555566/47825 478288.650015785639275e-20 4.920466254354166e-19https://cdsarc.cds.unistra.fr/viz-bin/moc/J/A+A/573/A92?format=asciiOpticaldefaultJ/A+A/573/A92/table7Abundances for blue horizontal-branch starsrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintStar[32170/77469] Star identification numbermeta.id;meta.mainintEW(Y)? Helium equivalent width (m{AA})0.1pmspect.line.eqWidthfloatnullableY[0.36/0.38]? Helium abundance (NLTE)phys.abund.Yfloatnullable[N/Fe]Abundance [N/Fe]log(Sun)phys.abundfloate_[N/Fe]rms uncertainty on [N/Fe]log(Sun)stat.error;phys.abundfloat[O/Fe]Abundance [O/Fe]log(Sun)phys.abundfloate_[O/Fe]rms uncertainty on [O/Fe]log(Sun)stat.error;phys.abundfloat[Na/Fe]Abundance [Na/Fe]log(Sun)phys.abundfloate_[Na/Fe]rms uncertainty on [Na/Fe]log(Sun)stat.error;phys.abundfloat[Mg/Fe]Abundance [Mg/Fe]log(Sun)phys.abundfloate_[Mg/Fe]? rms uncertainty on [Mg/Fe]log(Sun)stat.error;phys.abundfloatnullableJ/A+A/573/A92/table8Abundances for red horizontal-branch starsrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintStar[32170/77469] Star identification numbermeta.id;meta.mainint[Fe/H]Abundance [Fe/H]log(Sun)phys.abund.Fefloate_[Fe/H]rms uncertainty on [Fe/H]log(Sun)stat.error;phys.abund.Fefloat[O/Fe]Abundance [O/Fe]log(Sun)phys.abundfloate_[O/Fe]rms uncertainty on [O/Fe]log(Sun)stat.error;phys.abundfloat[Na/Fe]Abundance [Na/Fe]log(Sun)phys.abundfloate_[Na/Fe]rms uncertainty on [Na/Fe]log(Sun)stat.error;phys.abundfloat[Mg/Fe]? Abundance [Mg/Fe]log(Sun)phys.abundfloatnullable[Si/Fe]? Abundance [Si/Fe]log(Sun)phys.abundfloatnullablee_[Si/Fe]? rms uncertainty on [Si/Fe]log(Sun)stat.error;phys.abundfloatnullable[Ca/Fe]? Abundance [Ca/Fe]log(Sun)phys.abundfloatnullable[Ni/Fe]? Abundance [Ni/Fe]log(Sun)phys.abundfloatnullable[Ba/Fe]? Abundance [Ba/Fe]log(Sun)phys.abundfloatnullableJ/A+A/573/A92/starsPhotometric (table 2) and spectroscopic (table3) data, and atmospheric parameters (table5)recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintTypeStar type (G1)src.classcharStarStar identification numbermeta.id;meta.mainintprimaryRAJ2000Right ascension (J2000)degpos.eq.ra;meta.mainDEJ2000Declination (J2000)degpos.eq.dec;meta.mainVmagLLee et al. (2014ApJS..210....6L) V magnitudemagphot.mag;em.opt.VfloatBmagLLee et al. (2014ApJS..210....6L) B magnitudemagphot.mag;em.opt.BfloatVmag? V magnitude (Stetson et al., in prep.)magphot.mag;em.opt.VfloatnullableBmag? B magnitude (Stetson et al., in prep.)magphot.mag;em.opt.BfloatnullableJmag? 2MASS J magnitudemagphot.mag;em.IR.JfloatnullableHmag? 2MASS H magnitudemagphot.mag;em.IR.HfloatnullableKmag? 2MASS Ks magnitudemagphot.mag;em.IR.KfloatnullableS/N(12A)[14/31] Signal-to-noise ratio of HR12A set up (2011-07-11T07:14:23.5)stat.snrintS/N(12B)[23/48]? Signal-to-noise ratio of HR12B set up (2011-08-27T00:10:09.5)stat.snrintnullableS/N(19A)[33/75] Signal-to-noise ratio of HR19A set up (2011-07-18T06:03:41.7)stat.snrintS/N(19B)[35/69] Signal-to-noise ratio of HR19B set up (2011-07-18T06:52:18.1)stat.snrintRV(12A)[-110/-66]? Radial velocity from HR12A set upkm/sphys.veloc;pos.heliocentricfloatnullableRV(12B)[-110/-66]? Radial velocity from HR12B set upkm/sphys.veloc;pos.heliocentricfloatnullableRV(19A)[-110/-66]? Radial velocity from HR19A set upkm/sphys.veloc;pos.heliocentricfloatnullableRV(19B)[-110/-66]? Radial velocity from HR19B set upkm/sphys.veloc;pos.heliocentricfloatnullable<RV>[-105/-66]Mean radial velocitykm/sspect.dopplerVeloc;stat.meanfloate_<RV>[0.1/11] rms uncertainty on <RV>km/sstat.errorfloat<FWHM>[0.6/0.9]? Mean FWHM of the OI triplet (777nm)0.1nmspect.line.widthfloatnullablee_<FWHM>[0.01/0.06]? rms uncertainty on <FWHM>0.1nmstat.error;phys.angSizefloatnullablel_vsiniLimit flag on vsinimeta.code.error;phys.veloc.rotatcharvsini[5/15]? Rotational velocitykm/sphys.veloc.rotatfloatnullablee_vsini[0/4]? rms uncertainty on vsinikm/sstat.error;phys.veloc.rotatfloatnullableTeffEffective temperatureKphys.temperature.effectiveintnullablee_Teffrms uncertainty on TeffKstat.error;phys.temperature.effectiveintnullableloggSurface gravitylog(cm.s**-2)phys.gravityfloatnullablevtMicroturbulent velocitykm/sphys.velocfloatnullable[M/H][-1.25] Model metal abundance (fixed)log(Sun)phys.abund.Z;meta.modelledfloatnullableSimbadSimbad column added by the CDSmeta.ref.urlcharnullable