J/A+A/563/A13ivo://CDS.VizieR/J/A+A/563/A13doi:10.26093/cds/vizier.35630013CDSGratton R.G.Lucatello S.Sollima A.Carretta E.Bragaglia A.,Momany Y.D'Orazi V.Cassisi S.Salaris M.2017-06-26T11:50:06Z2014-02-26T13:38:58ZCDS support team

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

cds-question@unistra.frgalaxiesglobular-star-clusterschemical-abundanceshorizontal-branch-starsWe obtained high-resolution spectra for 94 candidate stars belonging to the HB of M 22 with FLAMES. Previous works have indicated that this cluster has split subgiant (SGB) and red giant branches (RGB) and hosts two different stellar populations, differing in overall metal abundance and both exhibiting a Na-O anti-correlation. The HB stars we observed span a restricted temperature range (7800<Teff<11000K), where about 60% of the HB stars of M 22 are. Within our sample, we can distinguish three groups of stars segregated (though contiguous) in colours: Group 1 (49 stars) is metal-poor, N-normal, Na-poor and O-rich: our abundances for this (cooler) group match very well those determined for the primordial group of RGB stars (a third of the total) from previous studies. Group 2 (23 stars) is still metal-poor, but it is N- and Na-rich, though only very mildly depleted in O. We can identify this intermediate group as the progeny of the metal-poor RGB stars that occupy an intermediate location along the Na-O anti-correlation and include about 10% of the RGB stars. The third group (20 stars) is metal-rich, Na-rich, and O-rich. This hotter group likely corresponds to the most O-rich component of the previously found metal-rich RGB population (a quarter of the total). We did not observe any severely O-depleted stars and we think that the progeny of these stars falls on the hotter part of the HB. Furthermore, we found that the metal-rich population is also over-abundant in Sr, in agreement with results for corresponding RGB and SGB stars. However, we do not find any significant variation in the ratio between the sum of N and O abundances to Fe. We do not have C abundances for our stars. There is some evidence of an enhancement of He content for Groups 2 and 3 stars (Y=0.338+/-0.014+/-0.05); the error bar due to systematics is large, but a consistent analysis of data for several GCs confirms that stars in these groups within M22 are likely overabundant in He. We conclude that on the whole, our results agree with the proposition that chemical composition drives the location of stars along the HB of a GC. Furthermore, we found a number of fast rotators. They are concentrated in a restricted temperature range along the HB of M22. Fast rotating stars might be slightly less massive and bluer than slowly rotating ones, but other interpretations are possible.2014A&A...563A..13Ghttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/563/A13CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toJ/ApJ/420/612 : Proper motions + radial velocities in M22 (Peterson+ 1994)J/PASP/107/32 : uvby-hk photometry in M22 (Anthony-Twarog+ 1995)J/A+A/373/899 : New variables in M22 globular cluster (Kaluzny+, 2001)J/MNRAS/349/1278 : BVI photometry of M22 (Monaco+, 2004)J/ApJ/742/37 : Abundances of six RGB stars in M22 (Roederer+, 2011)J/A+A/541/A15 : Abundances of M22 subgiants (Marino+, 2012)J/A+A/559/A101 : NGC6656 spectroscopy of 71 blue HB stars (Salgado+, 2013)J/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)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/563/A13https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/563/A13http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/563/A13https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/563/A13https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/563/A13http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/563/A13GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/A+A/563/A13/catalog (Catalog of horizontal- branch stars in M22)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/563/A13/catalog?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/563/A13/catalog?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/563/A13/catalog?GETtext/xml+votable180.050000true279.1168-24.007377780.0055555555555555566/28966-28967 28972-289738.650015785639275e-20 4.920466254354166e-19https://cdsarc.cds.unistra.fr/viz-bin/moc/J/A+A/563/A13?format=asciiOpticaldefaultJ/A+A/563/A13/catalogCatalog of horizontal- branch stars in M22VmagV magnitudemagphot.mag;em.opt.Vfloate_Vmagrms uncertainty on Vmagmagstat.error;phot.mag;em.opt.VfloatBmagB magnitudemagphot.mag;em.opt.Bfloate_Bmagrms uncertainty on Bmagmagstat.error;phot.mag;em.opt.BfloatImagI magnitudemagphot.mag;em.opt.Ifloate_Imagrms uncertainty on Imagmagstat.error;phot.mag;em.opt.IfloatKmag? 2MASS Ks magnitudemagphot.mag;em.IR.Kfloatnullableymag? Stromgren y magnitudemagphot.mag;em.opt.Vfloatnullablebmag? Stromgren b magnitudemagphot.mag;em.opt.Bfloatnullablevmag? Stromgren v magnitudemagphot.mag;em.opt.BfloatnullableE(B-V)Interstellar redenningmagphot.color.excessfloatS/N3? S/N with HR03 set upstat.snrintnullableS/N12? S/N with HR12 set upstat.snrintnullableS/N19? S/N with HR19 set upstat.snrintnullableRV03? Radial velocity with HR03 set upkm/sphys.veloc;pos.heliocentricdoublenullableRV12? Radial velocity with HR12 set upkm/sphys.veloc;pos.heliocentricdoublenullableRV19Radial velocity with HR19 set upkm/sphys.veloc;pos.heliocentricdouble<RV>Average radial velocitykm/sspect.dopplerVeloc;stat.meandoublee_<RV>? r.m.s. of radial velocitieskm/sstat.errorfloatnullableFWHM3? FWHM with HR03 set upkm/sspect.line.widthfloatnullableFWHM12? FWHM with HR12 set upkm/sspect.line.widthfloatnullableFWHM19? FWHM with HR19 set upkm/sspect.line.widthfloatnullable<FWHM>Average FWHM of spectral lineskm/sspect.line.widthfloate_<FWHM>? r.m.s. of FWHMkm/sstat.error;phys.angSizefloatnullablel_vsini[<] Limit flag on vsinimeta.code.error;phys.veloc.rotatcharvsini[5/50] Rotational velocitykm/sphys.veloc.rotatintTe(B-V)Effective temperature from B-VKphys.temperature.effectiveintTe(V-I)Effective temperature from V-IKphys.temperature.effectiveintTe(b-y)? Effective temperature from b-yKphys.temperature.effectiveintnullableTe(v-y)? Effective temperature from v-yKphys.temperature.effectiveintnullableTe(V-K)? Effective temperature from V-KKphys.temperature.effectiveintnullableTe(phot)Effective temperature from photKphys.temperature.effectiveinte_TeError on effective temperatureKstat.errorintTe(Hd)? Effective temperature from H{delta}Kphys.temperature.effectiveintnullablelogglog surface gravitylog(cm.s**-2)phys.gravityfloatvtMicroturbulence velocitykm/sphys.veloc.microTurbfloatYNLTE[0.2/0.5]? NLTE He abundancephys.abund.Yfloatnullablee_YNLTE[0.0/0.1]? error on YNLTEstat.errorfloatnullable[Fe/H]I? Abundance Fe/HIlog(Sun)phys.abund.Fedoublenullable[Fe/H]II? Abundance Fe/HIIlog(Sun)phys.abund.Fedoublenullable[Fe/H]? Mean Fe/H abundancelog(Sun)phys.abund.Fe;stat.meandoublenullable[N/Fe]? Abundance N/Felog(Sun)phys.abundfloatnullable[O/Fe]? Abundance O/Felog(Sun)phys.abundfloatnullable[Na/Fe]Abundance Na/Felog(Sun)phys.abunddouble[Mg/Fe]I? Abundance Mg/FeIlog(Sun)phys.abundfloatnullable[Mg/Fe]II? Abundance Mg/FeIIlog(Sun)phys.abundfloatnullable[Si/Fe]? Abundance Si/FeIIlog(Sun)phys.abundfloatnullable[Ti/Fe]? Abundance Ti/FeIIlog(Sun)phys.abundfloatnullable[Sr/Fe]? Abundance Sr/FeIIlog(Sun)phys.abunddoublenullableGr[ABC] Group designation (see section 4)meta.idcharRAJ2000Right ascension (J2000.0)pos.eq.ra;meta.mainDEJ2000Declination (J2000.0)pos.eq.dec;meta.mainStar[1/129] Star designationmeta.id;meta.mainintprimary