Stellar populations in $\omega$ Centauri: a multivariate analysis

Abstract

We have performed multivariate statistical analyses of photometric and chemical abundance parameters of three large samples of stars in the globular cluster $\omega$ Centauri. The statistical analysis of a sample of 735 stars based on seven chemical abundances with the method of Maximum Parsimony (cladistics) yields the most promising results: seven groups are found, distributed along three branches with distinct chemical, spatial and kinematical properties. A progressive chemical evolution can be traced from one group to the next, but also within groups, suggestive of an inhomogeneous chemical enrichment of the initial interstellar matter. The adjustment of stellar evolution models shows that the groups with metallicities [Fe/H]\textgreater{}-1.5 are Helium-enriched, thus presumably of second generation. The spatial concentration of the groups increases with chemical evolution, except for two groups, which stand out in their other properties as well. The amplitude of rotation decreases with chemical evolution, except for two of the three metal-rich groups, which rotate fastest, as predicted by recent hydrodynamical simulations. The properties of the groups are interpreted in terms of star formation in gas clouds of different origins. In conclusion, our multivariate analysis has shown that metallicity alone cannot segregate the different populations of $\omega$ Centauri.

References in corpus (55)

• Evolutionary tracks and isochrones for low- and intermediate-mass stars: from 0.15 to 7 M_sun, and from Z=0.0004 to 0.03
• The Dartmouth Stellar Evolution Database
• Nucleosynthesis in Chandrasekhar Mass Models for Type Ia Supernovae and Constraints on Progenitor Systems and Burning-Front Propagation
• Multiple populations in globular clusters. Lessons learned from the Milky Way globular clusters
• Na-O Anticorrelation and HB. VII. The chemical composition of first and second-generation stars in 15 globular clusters from GIRAFFE spectra
• Fast rotating massive stars and the origin of the abundance patterns in galactic globular clusters
• A Triple Main Sequence in the Globular Cluster NGC 2808
• 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)
• A helium spread among the main sequence stars in NGC 2808
• The dynamical distance and intrinsic structure of the globular cluster omega Centauri
• On the typical timescale for the chemical enrichment from SNeIa in Galaxies
• Early Disc Accretion as the Origin of Abundance Anomalies in Globular Clusters
• Theoretical isochrones in several photometric systems II. The Sloan Digital Sky Survey ugriz system
• New Limits on an Intermediate Mass Black Hole in Omega Centauri: I. Hubble Space Telescope Photometry and Proper Motions
• New evidence for the complex struscture of the RGB of Omega Cen
• The Role of Type Ia Supernovae in Chemical Evolution I: Lifetime of Type Ia Supernovae and Galactic Supernova Rates
• The origin of the double main sequence in Omega Centauri: Helium enrichment due to gas fueling from its ancient host galaxy ?
• Helium enhanced stars and multiple populations along the horizontal branch of NGC2808: direct spectroscopic measurements
• The Abundance Spread Among Giants and Subgiants in the Globular Cluster Omega Centauri
• Secondary star formation within massive star clusters: Origin of multiple stellar populations in globular clusters
• The influence of residual gas expulsion on the evolution of the Galactic globular cluster system and the origin of the Population II halo
• NGC 6441: another indication for a very high helium content in Globular Cluster stars
• Radial distribution of the multiple stellar populations in omega Centauri
• A model for the Globular Cluster extreme anomalies
• The Stellar Dynamics of Omega Centauri
• Hubble Space Telescope Observations of an Outer Field in Omega Centauri: A Definitive Helium Abundance
• The metallicity spread and the age-metallicity relation of Omega Centauri
• Rotation and multiple stellar population in globular clusters
• Star Formation Histories of Globular Clusters with Multiple Populations. I. ω Cen, M22, and NGC 1851
• The Rotation of Sub-Populations in omega Centauri
• The helium spread in the Globular cluster 47 Tuc
• The non-peculiar velocity dispersion profile of the stellar system omega Centauri
• Fe and Al Abundances for 180 Red Giants in the Globular Cluster Omega Centauri (NGC 5139)
• A Large Sample Study of Red Giants in the Globular Cluster Omega Centauri (NGC 5139)
• Dynamical Evolution of Rotating Stellar Systems: III. The Effect of Mass Spectrum
• Multiple populations in Omega Centauri: a cluster analysis of spectroscopic data
• Constraints on Helium Enhancement in the Globular Cluster M3 (NGC 5272): The Horizontal Branch Test
• Discovery of an accreted stellar system within the globular cluster omega Centauri
• Radial velocities in the globular cluster omega Centauri
• A spectral atlas of post-main-sequence stars in omega Centauri: kinematics, evolution, enrichment and interstellar medium
• Star Counts in the Globular Cluster Omega Centauri. I. Bright Stellar Components
• The oxygen vs. sodium (anti)correlation(s) in omega Cen
• The environment of formation as a second parameter for globular cluster classification
• Modeling the chemical evolution of Omega Centauri using three-dimensional hydrodynamical simulations
• A six-parameter space to describe galaxy diversification
• The fingerprint of binary intermediate mass black holes in globular clusters: supra-thermal stars and angular momentum alignment
• Towards a Phylogenetic Analysis of Galaxy Evolution : a Case Study with the Dwarf Galaxies of the Local Group
• Star Formation History of Omega Centauri Imprinted in Elemental Abundance Patterns
• Spectral matching for abundances and clustering analysis of stars on the giant branches of ω Centauri
• The subgiant branch of omega Cen seen through high-resolution spectroscopy. II. The most metal-rich population
• Type Ia supernovae in globular clusters: observational upper limits
• Spectral matching for abundances of 848 stars of the giant branches of the globular cluster ω Centauri
• The Production Rate of SN Ia Events in Globular Clusters

Cited by in corpus (10)

• Evidence from the H3 Survey that the Stellar Halo is Entirely Comprised of Substructure
• On the RR Lyrae stars in globulars: IV. $\omega$ Centauri Optical UBVRI Photometry
• Cosmic phylogeny: reconstructing the chemical history of the solar neighbourhood with an evolutionary tree
• Multivariate Approaches to Classification in Extragalactic Astronomy
• Cladistical analysis of the Jovian and Saturnian satellite systems
• Phylogenetic Analyses of Quasars and Galaxies
• Evolutionary history of four binary blue stragglers from the globular clusters ωCen, M55, 47 Tuc and NGC 6752
• Concepts of Classification and Taxonomy. Phylogenetic Classification
• Phylogenetic Tools in Astrophysics
• A phylogenetic analysis of galaxies in the Coma Cluster and the field: a new approach to galaxy evolution