Chemical tagging with APOGEE, Gaia, MUSE, and HST: constraints on the formation of ω Centauri

Mason, AC, Schiavon, RP ORCID: 0000-0002-2244-0897, Kamann, S ORCID: 0000-0001-6604-0505, Smith, VV, Horta, D, Anguiano, B, Cunha, K, Meszaros, S, Majewski, SR, O'connell, RW, Allende prieto, C and Saracino, S (2026) Chemical tagging with APOGEE, Gaia, MUSE, and HST: constraints on the formation of ω Centauri. Monthly Notices of the Royal Astronomical Society, 547 (4). ISSN 0035-8711

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Abstract

Current evidence suggests that w Cen is the nuclear star cluster of a galaxy that merged with the Milky Way at early times. We use Apache Point Observatory Galactic Evolution Experiment (APOGEE), Gaia, Multi Unit Spectroscopic Explorer, and Hubble Space Telescope data supplemented by galaxy chemical evolution models to place constraints on the assembly and chemical enrichment history of w Cen. The APOGEE data reveal three stellar populations occupying separate loci on canonical chemical planes. One population resembles metal-poor halo field stars (P1), a second shows light-element abundance anticorrelations typical of metal-poor globular clusters (IM), and a third population (P2) is characterized by an extreme ‘second-generation’ abundance pattern. Both P1 and P2 populations cover a broad range of metallicity, consistent with extended histories of bursty star formation (SF), which is also evident from their light and α-element abundance patterns. Conversely, the IM stars exhibit a narrow metallicity spread, combined with Al–Mg, Na–O, and C–N anticorrelations resembling metal-poor Galactic globular clusters. Moreover, these three populations alone seem to account for the distribution of w Cen stars in the chromosome map. We discuss these findings in the context of a scenario according to which w Cen formed by a combination of in situ SF within the host galaxy (P1), followed by the spiralling in of gas-rich globular clusters (IM), leading to another burst of SF (P2). We perform a robust comparison of the chemical composition of w Cen with those of halo substructures well represented in APOGEE DR17, finding no chemical associations to a high confidence level.

Item Type:	Article
Uncontrolled Keywords:	Galaxies: stellar content; globular clusters: general; globular clusters: individual; methods: numerical; stars: abundances; stars: Hertzsprung-Russell and colour-magnitude diagrams; methods: numerical; stars: abundances; stars: Hertzsprung-Russell and colour-magnitude diagrams; globular clusters: general; globular clusters: individual; Galaxies: stellar content; 5101 Astronomical Sciences; 51 Physical Sciences; 0201 Astronomical and Space Sciences; Astronomy & Astrophysics; 5101 Astronomical sciences; 5107 Particle and high energy physics; 5109 Space sciences
Subjects:	Q Science > QB Astronomy Q Science > QC Physics
Divisions:	Astrophysics Research Institute
Publisher:	Oxford University Press
Date of acceptance:	13 February 2026
Date of first compliant Open Access:	22 April 2026
Date Deposited:	22 Apr 2026 12:44
Last Modified:	22 Apr 2026 12:44
DOI or ID number:	10.1093/mnras/stag433
URI:	https://researchonline.ljmu.ac.uk/id/eprint/28427

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