J/A+A/707/A280ivo://CDS.VizieR/J/A+A/707/A280CDSAlvarez Garay D.A.Mucciarelli A.Ventura P.Bellazzini M.Covella S.2026-04-02T06:28:33Z2026-03-23T10:00:30ZCDS support team

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

cds-question@unistra.frglobular-star-clusterschemical-abundancesspectroscopyvisible-astronomyradial-velocityeffective-temperaturegalaxy-kinematicsIn this study, we present the chemical abundances of Fe, Mg, Al, Si, and K for a sample of 233 likely member stars of M 54. All the stars were observed with the FLAMES high-resolution multi-object spectrograph mounted at the VLT. Our analysis confirmed the presence of a large metallicity range in M 54, with the majority of the stars having -1.8<[Fe/H]<-1.0 dex and few stars with [Fe/H]>-1.0dex. The mean value of the total sample is [Fe/H]=-1.40 (sigma=0.22dex). A MCMC analysis revealed that the observed spread in [Fe/H] is compatible with a non-null intrinsic iron dispersion. We also found that the metallicity distribution function and the broadening of the red giant branch of M 54 are not compatible with a single age, but instead they suggest a wide age range from about 13 Gyr to about 1-2Gyr or a smaller age range if a significant He enhancement (Y=0.35/0.40) is present in the most metal-rich stars. We identified among the stars in M 54 the entire pattern of anticorrelations linked to the MgAl burning cycle. In particular, the metal-rich component displays a higher level of H-burning with the presence of more extended anticorrelations than the metal-poor component. No Mg-poor ([Mg/Fe]<0.0dex) stars are identified in M 54. The evidence collected so far cannot be explained neither with a GC-like scenario nor with a galactic chemical evolution. The chemical properties of M 54 can be explained within a scenario where this system formed through the merging of two globular clusters, the metal-poor one with standard characteristics and the more metal-rich one with more pronounced chemical anomalies, a possibly younger than the first one. M 54 is confirmed as a key stellar system for explaining the chemical evolution of a nuclear star cluster.2026A&A...707A.280Ahttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/707/A280CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toI/355 : Gaia DR3 Part 1. Main source (Gaia Collaboration, 2022)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/707/A280https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/707/A280http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/707/A280https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/707/A280https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/707/A280http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/707/A280GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/A+A/707/A280/table2 (Stellar parameters and chemical abundances of likely member stars of M 54 observed with FLAMES)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/707/A280/table2?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/707/A280/table2?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/707/A280/table2?GETtext/xml+votable180.050000true283.7829822-30.41747640.0055555555555555566/48035 480411.9867573869263685e-19 3.916500758235022e-19https://cdsarc.cds.unistra.fr/viz-bin/moc/J/A+A/707/A280?format=asciiOpticaldefaultJ/A+A/707/A280/table2Stellar parameters and chemical abundances of likely member stars of M 54 observed with FLAMESrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintIDStar name identifier number, M54_NNNNNNN (ID)meta.id;meta.maincharGaiaDR3Gaia DR3 star name (ID_Gaia)meta.idGmagGaia DR3 G magnitude (G_0_)magphot.mag;em.optfloatRVRadial velocity (RV)km/sphys.veloc;pos.heliocentricfloate_RVError in radial velocity (eRV)km/sstat.errorfloatTeffSurface temperature (Teff)Kphys.temperature.effectiveintloggLogarithm of star gravity (logg)log(cm.s**-2)phys.gravityfloatVtMicroturbolent velocity (v_t)km/sphys.veloc.microTurbfloat[Fe/H]Abundance relative to the Sun for FeI ([Fe/H])log(Sun)phys.abund.Fefloate_[Fe/H]Uncertainty on the abundance for FeI (e[Fe/H])log(Sun)stat.error;phys.abund.Fefloat[Mg/Fe]? Abundance relative to the Sun for MgI ([Mg/Fe])log(Sun)phys.abundfloatnullablee_[Mg/Fe]? Uncertainty on the abundance for MgI (e[Mg/Fe])log(Sun)stat.error;phys.abundfloatnullable[Al/Fe]? Abundance relative to the Sun for AlI ([Al/Fe])log(Sun)phys.abundfloatnullablee_[Al/Fe]? Uncertainty on the abundance for AlI (e[Al/Fe])log(Sun)stat.error;phys.abundfloatnullable[Si/Fe]? Abundance relative to the Sun for SiI ([Si/Fe])log(Sun)phys.abundfloatnullablee_[Si/Fe]? Uncertainty on the abundance for SiI (e[Si/Fe])log(Sun)stat.error;phys.abundfloatnullable[K/Fe]? Abundance relative to the Sun for KI ([K/Fe])log(Sun)phys.abundfloatnullablee_[K/Fe]? Uncertainty on the abundance for KI (e[K/Fe])log(Sun)stat.error;phys.abundfloatnullable_RAPosition from I/355 GaiaDR3 catalog (right ascension part)degpos.eq.ra;meta.main_DEPosition from I/355 GaiaDR3 catalog (declination part)degpos.eq.dec;meta.main