J/A+A/712/A6ivo://CDS.VizieR/J/A+A/712/A6CDSPagnini G.Bianchini P.Di Matteo P.Mastrobuono-Battisti A.2026-07-30T12:33:15Z2026-07-30T13:27:08ZCDS support team

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

cds-question@unistra.frglobular-star-clustersgiant-starschemical-abundancesstellar-populationsThe origin of omega Centauri remains one of the key open problems in stellar dynamics and chemical evolution. Its large abundance spreads and multiple populations suggest a formation history more complex than that of a typical globular cluster. Aims. We investigate whether the chemical sub-populations identified in APOGEE DR17 also exhibit distinct spatial and kinematic signatures, and what constraints these provide on the formation pathways of omega Cen. We analyse a sample of APOGEE DR17 red-giant stars using a Gaussian Mixture Model in an eight-dimensional chemical-abundance space. The resulting chemical components are combined with Gaia proper motions and APOGEE line-of-sight velocities to derive intrinsic mean velocities and velocity dispersions in all three observable directions. We measure both global kinematic quantities and radial profiles for each chemically defined group, extending from the inner regions to ~4 half-light radii. The Gaussian Mixture Model identifies five chemical components, which, when examined through their radial cumulative distributions, naturally group into two broader families characterised by lower and higher aluminium enrichment. The two families differ significantly in their spatial and kinematic properties: the Al-rich stars are more centrally concentrated and exhibit stronger radial anisotropy than the Al-poor stars, which remain closer to isotropy over the radial range probed. Despite these significant differences (>2{sigma}), the two populations share a common rotation pattern, with comparable intrinsic rotation amplitudes and rotation-axis inclinations within the uncertainties (~0.5km/s). Both families span a wide range in metallicity, indicating that they do not simply correspond to a first- and second-generation dichotomy, but rather trace chemically and dynamically complex substructures within omega Cen. This work represents the first chemo-dynamical study of omega Cen linking detailed chemical tagging to internal kinematics from the inner regions to the cluster outskirts, and provides a key benchmark for models of its formation. A formation path involving both hierarchical assembly within a dwarf-galaxy potential and centrally concentrated, chemically enriched star formation offers a natural explanation for the observed chemo-dynamical complexity. Extending this approach to larger fields of view and to more numerous, fainter stars will be essential to robustly uncover the origin of this uniquely complex system.2026A&A...712A...6Phttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/712/A6CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toIII/286 : APOGEE-2 DR17 final allStar catalog (Abdurro'uf+, 2022)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/712/A6https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/712/A6http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/712/A6https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/712/A6https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/712/A6http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/712/A6GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/A+A/712/A6/tablea1 (APOGEE IDs and GMM labels)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/712/A6/tablea1?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/712/A6/tablea1?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/712/A6/tablea1?GETtext/xml+votable180.050000true200.8928367-47.57868530.0055555555555555566/43225 43227-43228 43230https://cdsarc.cds.unistra.fr/viz-bin/moc/J/A+A/712/A6?format=asciidefaultJ/A+A/712/A6/tablea1APOGEE IDs and GMM labelsrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintAPOGEEAPOGEE DR17 identifiermeta.id;meta.maincharComp[0/4] Assigned GMM component labelmeta.idintSimbadSimbad column added by the CDSmeta.ref.urlchar_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