The metallicity spread and the age-metallicity relation of Omega Centauri

Abstract

Omega Centauri is a peculiar Globular Cluster formed by a complex stellar population. To shed light on this, we studied 172 stars belonging to the 5 SGBs that we can identify in our photometry, in order to measure their [Fe/H] content as well as estimate their age dispersion and the age-metallicity relation. The first important result is that all of these SGBs has a distribution in metallicity with a spread that exceeds the observational errors and typically displays several peaks that indicate the presence of several sub-populations. We were able to identified at least 6 of them based on their mean [Fe/H] content. These metallicity-based sub-populations are seen to varying extents in each of the 5 SGBs. Taking advantage of the age-sensitivity of the SGB we showed that, first of all, at least half of the sub-populations have an age spread of at least 2 Gyrs. Then we obtained an age-metallicity relation that is the most complete up to date for this cluster. The interpretation of the age-metallicity relation is not straightforward, but it is possible that the cluster (or what we can call its progenitor) was initially composed of two populations having different metallicities. Because of their age, it is very unlikely that the most metal-rich derives from the most metal-poor by some kind of chemical evolution process, so they must be assumed as two independent primordial objects or perhaps two separate parts of a single larger object, that merged in the past to form the present-day cluster.

arXiv comment20 pages, 8 figures, accepted for publication on ApJ

References in corpus (23)

• A large stellar evolution database for population synthesis studies. II. Stellar models and isochrones for an alpha-enhanced metal distribution
• Omega Centauri: The Population Puzzle Goes Deeper
• Metallicities on the Double Main Sequence of omega Centauri Imply Large Helium Enhancement
• Chemical Abundances for 855 Giants in the Globular Cluster Omega Centauri (NGC 5139)
• The dynamical distance and intrinsic structure of the globular cluster omega Centauri
• The ACS Survey of Galactic Globular Clusters. III. The Double Subgiant Branch of NGC 1851
• The multiplicity of the subgiant branch of Omega Centauri: Evidence for prolonged star formation
• Transforming observational data and theoretical isochrones into the ACS/WFC Vega-mag system
• The double Subgiant Branch of NGC 1851: the role of the CNO abundance
• Sodium-oxygen anticorrelation and neutron capture elements in Omega Centauri stellar populations
• The Abundance Spread Among Giants and Subgiants in the Globular Cluster Omega Centauri
• Metallicities, relative ages and kinematics of stellar populations in omega Centauri
• First stars X. The nature of three unevolved Carbon-Enhanced Metal-Poor stars
• The C+N+O abundance of Omega Centauri giant stars: implications on the chemical enrichment scenario and the relative ages of different stellar populations
• On the Origin of the High Helium Sequence in $\omega$ Centauri
• Hubble Space Telescope Observations of an Outer Field in Omega Centauri: A Definitive Helium Abundance
• Star Formation Histories of Globular Clusters with Multiple Populations. I. ω Cen, M22, and NGC 1851
• The extended star formation history of omega Centauri
• The Age and Metallicity Relation of Omega Centauri
• Stromgren photometry of Galactic Globular Clusters. II Metallicity distribution of red giants in Omega Centauri
• Radial velocities in the globular cluster omega Centauri
• The subgiant branch of omega Cen seen through high-resolution spectroscopy. I. The first stellar generation in omega Centauri?
• Chemical enrichment mechanisms in Omega Centauri: clues from neutron-capture elements

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• The Hubble Space Telescope UV Legacy Survey of Galactic Globular Clusters. IX. The Atlas of Multiple Stellar Populations
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• Target Selection for the SDSS-IV APOGEE-2 Survey
• What is a globular cluster? An observational perspective
• N-body modeling of globular clusters: Masses, mass-to-light ratios and intermediate-mass black holes
• The Hubble Space Telescope UV Legacy Survey of Galactic Globular Clusters. II. The seven stellar populations of NGC7089 (M2)
• Ceci n'est pas a globular cluster: the metallicity distribution of the stellar system Terzan 5
• A Spectroscopic Analysis of the Galactic Globular Cluster NGC 6273 (M19)
• The dwarf galaxy satellite system of Centaurus A
• The State-of-the-Art HST Astro-Photometric Analysis of the core of ωCentauri. III. The Main Sequence's Multiple Populations Galore
• A deep view into the nucleus of the Sagittarius Dwarf Spheroidal Galaxy with MUSE. I. Data and stellar population characterization
• The Outer Envelopes of Globular Clusters. I. NGC 7089 (M2)
• Discovery of a Metal-Poor Field Giant with a Globular Cluster Second-Generation Abundance Pattern
• Diversity of nuclear star cluster formation mechanisms revealed by their star formation histories
• The HST Large Program on Omega Centauri. I. Multiple stellar populations at the bottom of the main sequence probed in NIR-Optical
• Beyond spectroscopy. I. Metallicities, distances, and age estimates for over twenty million stars from SMSS DR2 and Gaia EDR3
• Radial anisotropy in omega Cen limiting the room for an intermediate-mass black hole
• The Hubble Space Telescope UV Legacy Survey of Galactic Globular Clusters. IV. Helium content and relative age of multiple stellar populations within NGC 6352
• The SLUGGS Survey: Measuring globular cluster ages using both photometry and spectroscopy
• The mosaic multiple stellar populations in $\omega$ Centauri : the Horizontal Branch and the Main Sequence
• A critical look at the merger scenario to explain multiple populations and rotation in iron-complex globular clusters
• Multiple stellar populations and their evolution in globular clusters: A nucleosynthesis perspective
• A spectroscopic study of the Globular Cluster M28 (NGC~6626)
• A deep view into the nucleus of the Sagittarius Dwarf Spheroidal Galaxy with MUSE. II. Kinematic characterization of the stellar populations
• The State-of-the-Art HST Astro-Photometric Analysis of the core of $\omega$ Centauri. II. Differential-Reddening Map
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• Galactic ArchaeoLogIcaL ExcavatiOns (GALILEO) I. An updated census of APOGEE N-rich giants across the Milky Way
• The Hubble Space Telescope UV Legacy Survey of Galactic Globular Clusters. XX. Ages of single and multiple stellar populations in seven bulge globular clusters
• oMEGACat I: MUSE spectroscopy of 300,000 stars within the half-light radius of $\omega$ Centauri
• The WAGGS project - II. The reliability of the calcium triplet as a metallicity indicator in integrated stellar light
• NGC 3628-UCD1: A possible $\omega$ Cen Analog Embedded in a Stellar Stream
• The Most Metal-poor Stars in Omega Centauri (NGC 5139)
• A stellar census in globular clusters with MUSE -- Extending the CaT-metallicity relation below the horizontal branch and applying it to multiple populations
• Chemical Compositions of Field and Globular Cluster RR~Lyrae Stars: II. omega Centauri
• Nuclear Star Clusters in Cosmological Simulations
• MgAl burning chain in Omega Centauri
• The period-age relation of long-period variables
• Blue straggler masses from pulsation properties. II. Topology of the Instability Strip
• CAPOS: The bulge Cluster APOgee Survey III. Spectroscopic Tomography of Tonantzintla 2
• oMEGACat II -- Photometry and proper motions for 1.4 million stars in Omega Centauri and its rotation in the plane of the sky
• A Halo Substructure in Gaia Data Release 1
• Detecting Globular Cluster Tidal Extensions with Bayesian Inference: I. Analysis of $\omega$ Centauri with Gaia EDR3
• G2C2 - IV: A novel approach to study the radial distributions of multiple populations in Galactic globular clusters
• Abundance ties: Nephele and the globular cluster population accreted with $\omega$ Cen. Based on APOGEE DR17 and Gaia EDR3
• A stellar census in globular clusters with MUSE. A new perspective on the multiple main sequences of $\omega$ Centauri
• Lithium abundance in lower red giant branch stars of Omega Centauri
• Stellar populations in $\omega$ Centauri: a multivariate analysis
• A possible formation channel for blue hook stars in globular cluster - II. Effects of metallicity, mass ratio, tidal enhancement efficiency and helium abundance
• oMEGACat. VI. Analysis of the overall kinematics of Omega Centauri in 3D: velocity dispersion, kinematic distance, anisotropy, and energy equipartition
• Habitability in the Omega Centauri Cluster
• The Massive M31 Cluster G1: Detailed Chemical Abundances from Integrated Light Spectroscopy
• Intrinsic Metallicity Variation in the Intermediate Mass Type II Globular Cluster NGC 1261
• Tidal debris from Omega Centauri discovered with unsupervised machine learning
• Is Terzan 5 the remnant of a building block of the Galactic bulge? Evidence from APOGEE
• Chemical analysis of the Bulge Globular Cluster NGC 6553
• Evolution of long-lived globular cluster stars IV. Initial helium content and white-dwarf properties
• The bulge globular cluster Terzan 6 as seen from multi-conjugate adaptive optics and HST
• The Populations of Carina. I. Decoding the Color--Magnitude Diagram
• Neutron-capture elements in NGC 6752 multiple populations
• Kinematics of metallicity populations in Omega Centauri using Gaia Focused Product Release and Hubble Space Telescope
• Omega Centauri: weak MgH-band in red giants directly trace the helium content
• Chemical tagging with APOGEE, MUSE, and HST: constraints on the formation of $\omega$ Centauri
• The Nephele ecosystem: stars, globular clusters, and stellar streams associated with the progenitor galaxy of $\omega$ Centauri
• A population of luminous globular clusters and stripped nuclei with elevated mass to light ratios around NGC 5128
• Purveyors of fine halos III. Chemical abundance analysis of a potential omega Cen associate
• Search for Stellar Streams Based on Data from the RAVE5 and Gaia TGAS Catalogues
• Disruption of a Giant: Spectroscopic Identification of Members in the Periphery and Tidal Tails of $\omega$ Centauri