A stellar census in globular clusters with MUSE. A new perspective on the multiple main sequences of $\omega$ Centauri

Abstract

$\omega$ Cen is a rare example of a globular cluster where the iron abundance of the stars spans more than one order of magnitude. Many spectroscopic investigations of its red-giant- and sub-giant- branches have revealed multiple peaks in the iron abundance distribution. The metallicity distribution of main-sequence (MS) stars is not well characterized yet, due to the faintness of the stars and lack of data. So far, almost all studies of MS stars are based on photometric measurements. Our goal is to investigate the metallicity distribution of a statistically significant sample of MS stars in $\omega$ Cen. In particular, we aim at revisiting the metallicity difference between the red and blue MS of the cluster. We used MUSE spectra obtained for the central region of $\omega$ Cen to derive metallicities for $\approx$4200 MS stars. We find that blue MS stars are on average $\approx$0.1 dex more metal-rich than their red counterparts. On the basis of this new estimate, we find that the two sequences can be fit on the Hubble Space Telescope color-magnitude diagram with two isochrones having the same global metallicity and age but a higher helium abundance for the blue MS, that is $\Delta Y\lesssim$ 0.1. Furthermore, we determine the average metallicity of the five main populations along $\omega$ Cen MS and these estimates are consistent with expectations from previous photometric studies.

9 pages, 7 figures, Accepted for publication in A&A

References in corpus (48)

• emcee: The MCMC Hammer
• A new extensive library of PHOENIX stellar atmospheres and synthetic spectra
• A new generation of PARSEC-COLIBRI stellar isochrones including the TP-AGB phase
• 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
• A catalogue of masses, structural parameters and velocity dispersion profiles of 112 Milky Way globular clusters
• The ACS Survey of Galactic Globular Clusters. I. Overview and Clusters Without Previous HST Photometry
• Metallicities on the Double Main Sequence of omega Centauri Imply Large Helium Enhancement
• Origin of the system of globular clusters in the Milky Way
• Multiple Stellar Populations in the Globular Cluster omega Centauri as Tracers of a Merger Event
• The Data Processing Pipeline for the MUSE Instrument
• Chemical Abundances for 855 Giants in the Globular Cluster Omega Centauri (NGC 5139)
• A stellar census in globular clusters with MUSE: The contribution of rotation to cluster dynamics studied with 200 000 stars
• The multiplicity of the subgiant branch of Omega Centauri: Evidence for prolonged star formation
• New evidence for the complex struscture of the RGB of Omega Cen
• Resolving stellar populations with crowded field 3D spectroscopy
• Sodium-oxygen anticorrelation and neutron capture elements in Omega Centauri stellar populations
• The origin of the double main sequence in Omega Centauri: Helium enrichment due to gas fueling from its ancient host galaxy ?
• The State-of-the-Art HST Astro-Photometric Analysis of the core of $\omega$ Centauri. I. The Catalog
• The Abundance Spread Among Giants and Subgiants in the Globular Cluster Omega Centauri
• Metallicities, relative ages and kinematics of stellar populations in omega Centauri
• MUSE crowded field 3D spectroscopy of over 12,000 stars in the globular cluster NGC 6397 - I. The first comprehensive spectroscopic HRD of a globular cluster
• Hubble Space Telescope Observations of an Outer Field in Omega Centauri: A Definitive Helium Abundance
• MUSE crowded field 3D spectroscopy of over 12,000 stars in the globular cluster NGC 6397 - II. Probing the internal dynamics and the presence of a central black hole
• The metallicity spread and the age-metallicity relation of Omega Centauri
• The Accreted Nuclear Clusters of the Milky Way
• 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 extended star formation history of omega Centauri
• On the RR Lyrae stars in globulars: IV. $\omega$ Centauri Optical UBVRI Photometry
• The Age and Metallicity Relation of Omega Centauri
• The HST Large Program on Omega Centauri. I. Multiple stellar populations at the bottom of the main sequence probed in NIR-Optical
• Stromgren photometry of Galactic Globular Clusters. II Metallicity distribution of red giants in Omega Centauri
• The multiple stellar population in omega Centauri: spatial distribution and structural properties
• The mosaic multiple stellar populations in $\omega$ Centauri : the Horizontal Branch and the Main Sequence
• Reddening distribution across the center of the globular cluster Omega Centauri
• Star Counts in the Globular Cluster Omega Centauri. I. Bright Stellar Components
• A critical look at the merger scenario to explain multiple populations and rotation in iron-complex globular clusters
• The subgiant branch of omega Cen seen through high-resolution spectroscopy. I. The first stellar generation in omega Centauri?
• Homogeneous Analysis of Globular Clusters from the APOGEE Survey with the BACCHUS Code $-$ III. $\omega$ Cen
• Medium resolution spectroscopy in Omega Centauri: abundances of 400 subgiant and turn-off region
• A stellar census in globular clusters with MUSE -- Extending the CaT-metallicity relation below the horizontal branch and applying it to multiple populations
• The Most Metal-poor Stars in Omega Centauri (NGC 5139)
• The not so simple globular cluster $\omega$ Cen. I. Spatial distribution of the multiple stellar populations
• The Mass Function of omega Centauri down to 0.15 M_s
• Mergers of multi-metallic globular clusters: The role of dynamics
• The not so simple stellar system Omega Cen. II. Evidence in support of a merging scenario
• Merged or monolithic? Using machine-learning to reconstruct the dynamical history of simulated star clusters

Cited by in corpus (6)

• oMEGACat I: MUSE spectroscopy of 300,000 stars within the half-light radius of $\omega$ Centauri
• The HST large programme on $\omega$ Centauri -- V. Exploring the Ultracool Dwarf Population with Stellar Atmosphere and Evolutionary Modelling
• oMEGACat III. Multi-band photometry and metallicities reveal spatially well-mixed populations within $\omega$ Centauri's half-light radius
• Tidal debris from Omega Centauri discovered with unsupervised machine learning
• Reliable stellar abundances of individual stars with the MUSE integral-field spectrograph
• Globular Cluster UVIT legacy Survey (GlobUleS) III. Omega Centauri in Far-Ultraviolet