J/A+A/681/A54ivo://CDS.VizieR/J/A+A/681/A54doi:10.26093/cds/vizier.36810054CDSAlvarez Garay D.A.Mucciarelli A.Bellazzini M.Lardo C.Ventura P.2024-11-28T20:05:55Z2024-01-10T08:23:18ZCDS support team

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

cds-question@unistra.frglobular-star-clustersgiant-starschemical-abundancesspectroscopyvisible-astronomyIn this study, we report the results of the analysis of Fe, Mg, Al, and Si abundances analysis for a sample of 439 stars in Omega Centauri, using high-resolution spectra obtained with the VLT/FLAMES multi-object spectrograph. Our analysis reveals the presence of four distinct Fe populations, with the main peak occurring at a low metallicity, consistent with previous literature findings. We observe a discrete and pronounced Mg-Al anticorrelation, which exhibits variations in shape and extension as a function of metallicity. Specifically, this anticorrelation is present in stars with metallicities lower than approximately -1.3dex, while it becomes less evident or absent for higher [Fe/H] values. Additionally, we detect (anti)correlations between Mg and Si, and between Al and Si, whose extensions also vary with metallicity, similar to the Mg-Al anticorrelation. These results suggest that the MgAl cycle plays a crucial role in the formation of multiple populations in Omega Centauri, with the presence of all (anti)correlations at metallicities lower than -1.3dex, providing evidence for the burning of Mg at very high temperatures (>10^8^K), at least in the metal-poor regime. Furthermore, we observe a clear trend of stars with [Al/Fe]>+0.5dex as a function of metallicity, confirming for the first time the existence of the two channels of Al production and destruction. This evidence can help to provide further constraints on the potential nature of the polluters responsible for the observed chemical anomalies in this stellar system. Finally, we find that the two most metal-poor populations identified in our sample are compatible with null or very small metallicity dispersion and we discuss how this result fits into a scenario where Omega Centauri is the remnant of a disrupted nucleated dwarf galaxy.2024A&A...681A..54Ahttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/681/A54CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toJ/ApJ/722/1373 : {omega} Centauri giants abundances (Johnson+, 2010)J/ApJ/731/64 : Spectroscopy of 300 RGBs in {omega} Cen (Marino+, 2011)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/681/A54https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/681/A54http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/681/A54https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/681/A54https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/681/A54http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/681/A54GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/A+A/681/A54/table1 (Star names and chemical abundances of the observed targets)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/681/A54/table1?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/681/A54/table1?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/681/A54/table1?GETtext/xml+votable180.050000true201.7877147-47.39397470.0055555555555555566/43225 43227https://cdsarc.cds.unistra.fr/viz-bin/moc/J/A+A/681/A54?format=asciiOpticaldefaultJ/A+A/681/A54/table1Star names and chemical abundances of the observed targetsSimbadNameSimbad column added by the CDSmeta.idcharnullablerecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintIDStar name (NNNNNN_AAA) (1)meta.id;meta.mainchar[Fe/H]Abundance relative to the Sun for FeIphys.abundfloate_[Fe/H]Uncertainty on the abundance for FeIstat.error;phys.abund.Fefloat[Mg/Fe]? Abundance relative to the Sun for MgIphys.abundfloatnullablee_[Mg/Fe]? Uncertainty on the abundance for MgIstat.error;phys.abundfloatnullable[Al/Fe]? Abundance relative to the Sun for AlIphys.abundfloatnullablee_[Al/Fe]? Uncertainty on the abundance for AlIstat.error;phys.abundfloatnullable[Si/Fe]? Abundance relative to the Sun for SiIphys.abundfloatnullablee_[Si/Fe]? Uncertainty on the abundance for SiIstat.error;phys.abundfloatnullable_RARight Ascension (J2000) from SIMBAD (not part of the original data)degpos.eq.ra;meta.main_DEDeclination (J2000) from SIMBAD (not part of the original data)degpos.eq.dec;meta.main