The HST Large Program on Omega Centauri. I. Multiple stellar populations at the bottom of the main sequence probed in NIR-Optical

Abstract

As part of a large investigation with Hubble Space Telescope to study the faintest stars within the globular cluster Omega Centauri, in this work we present early results on the multiplicity of its main sequence (MS) stars, based on deep optical and near-infrared observations. By using appropriate color-magnitude diagrams we have identified, for the first time, the two main stellar populations I, and II along the entire MS, from the turn-off towards the hydrogen-burning limit. We have compared the observations with suitable synthetic spectra of MS stars and conclude that the two MSs are consistent with stellar populations with different metallicity, helium, and light-element abundance. Specifically, MS-I corresponds to a metal-poor stellar population ([Fe/H]~-1.7) with Y~ 0.25 and [O/Fe]~0.30. The MS-II hosts helium-rich (Y~0.37-0.40) stars with metallicity ranging from [Fe/H]~-1.7 to -1.4. Below the MS knee (mF160W~19.5, our photometry reveals that each of the two main MSs hosts stellar subpopulations with different oxygen abundances, with very O-poor stars ([O/Fe]~-0.5) populating the MS-II. Such a complexity has never been observed in previous studies of M-dwarfs in globular clusters. A few months before the lunch of the James Webb Space Telescope, these results demonstrate the power of optical and near-infrared photometry in the study of multiple stellar populations in globular clusters.

13 pages, 9 figures, accepted for publication in MNRAS

References in corpus (10)

• The Dartmouth Stellar Evolution Database
• Gaia Data Release 1: Astrometry - one billion positions, two million proper motions and parallaxes
• The Hubble Space Telescope UV Legacy Survey of Galactic Globular Clusters. IX. The Atlas of Multiple Stellar Populations
• The double Subgiant Branch of NGC 1851: the role of the CNO abundance
• Multiple stellar populations in Magellanic Clouds clusters. I. An ordinary feature for intermediate age globulars in the LMC?
• The Hubble Space Telescope UV Legacy Survey of Galactic Globular Clusters. II. The seven stellar populations of NGC7089 (M2)
• The metallicity spread and the age-metallicity relation of Omega Centauri
• Helium and Multiple Populations in the Massive Globular Cluster NGC6266 (M62)
• Fe and Al Abundances for 180 Red Giants in the Globular Cluster Omega Centauri (NGC 5139)
• Stellar Models of Multiple Populations in Globular Clusters. I. The Main Sequence of NGC 6752

Cited by in corpus (42)

• What is a globular cluster? An observational perspective
• The Hubble Space Telescope UV Legacy Survey of Galactic Globular Clusters. XIX. A Chemical Tagging of the Multiple Stellar Populations Over the Chromosome Maps
• The Parallax of Omega Centauri Measured from Gaia EDR3 and a Direct, Geometric Calibration of the Tip of the Red Giant Branch and the Hubble Constant
• The HST large programme on $\omega$ Centauri - II. internal kinematics
• The State-of-the-Art HST Astro-Photometric Analysis of the core of ωCentauri. III. The Main Sequence's Multiple Populations Galore
• The HST Large Programme on NGC6752. II. Multiple populations at the bottom of the main sequence probed in NIR
• Four stellar populations and extreme helium variation in the massive outer-halo globular cluster NGC 2419
• The HST large programme on $\omega$ Centauri -- III. Absolute proper motion
• A deep view into the nucleus of the Sagittarius Dwarf Spheroidal Galaxy with MUSE. II. Kinematic characterization of the stellar populations
• Multiple populations in massive star clusters under the magnifying glass of photometry: Theory and tools
• oMEGACat I: MUSE spectroscopy of 300,000 stars within the half-light radius of $\omega$ Centauri
• Survey of multiple populations in globular clusters among very low-mass stars
• Chromosome maps of Globular Clusters from wide-field ground-based photometry
• The Age of the Old Metal-Poor Globular Cluster NGC6397 Using WFC3/IR Photometry
• The HST large programme on omega Centauri -- IV. catalogue of two external fields
• MOCCA: Dynamics and evolution of binary stars of multiple stellar populations in tidally filling and underfilling globular star clusters
• The HST large programme on $\omega$ Centauri -- V. Exploring the Ultracool Dwarf Population with Stellar Atmosphere and Evolutionary Modelling
• Star clusters forming in a low metallicity starburst -- rapid self-enrichment by (very) massive stars
• oMEGACat III. Multi-band photometry and metallicities reveal spatially well-mixed populations within $\omega$ Centauri's half-light radius
• High-precision abundances of first population stars in NGC 2808: confirmation of a metallicity spread
• The not so simple stellar system Omega Cen. II. Evidence in support of a merging scenario
• oMEGACat II -- Photometry and proper motions for 1.4 million stars in Omega Centauri and its rotation in the plane of the sky
• Detecting Globular Cluster Tidal Extensions with Bayesian Inference: I. Analysis of $\omega$ Centauri with Gaia EDR3
• A chromosome map to unveil stellar populations with different magnesium abundances. The case of Omega Centauri
• The HST Large Programme on NGC 6752. III. Detection of the Peak of the White Dwarf Luminosity Function
• A stellar census in globular clusters with MUSE. A new perspective on the multiple main sequences of $\omega$ Centauri
• Astrometry with the Wide-Field InfraRed Space Telescope
• Habitability in the Omega Centauri Cluster
• Models of Metal-Poor Stars with Different Initial Abundances of C, N, O, Mg, and Si. I. Bolometric Corrections Derived from New MARCS Synthetic Spectra and Their Implications for Observed Colour-Magnitude Diagrams
• The VMC survey XXVIII. Improved measurements of the proper motion of the Galactic globular cluster 47 Tucanae
• MOCCA: Global properties of tidally filling and underfilling globular star clusters with multiple stellar populations
• Chemical analysis of the Bulge Globular Cluster NGC 6553
• Exploring the formation environment of multiple stellar populations in Globular Clusters through binary systems
• Towards Realistic Modeling of the Astrometric Capabilities of MCAO Systems: Detecting an Intermediate Mass Black Hole with MAVIS
• Helium Enhancement in the Metal Rich Red Giants of Omega Centauri
• A Universal Transition in Atmospheric Diffusion for Hot Subdwarfs Near 18,000 K
• New sub-grouping of multiple stellar populations in NGC 2808 based on low-resolution spectroscopy
• Chemical tagging with APOGEE, MUSE, and HST: constraints on the formation of $\omega$ Centauri
• Exploring Multiple Stellar Populations in Globular Clusters with Euclid: A Theoretical Overview and Insights from NGC 6397
• Thirteen facts that you need to know on multiple populations in globular clusters
• Spectroscopic studies of stellar populations in globular clusters and field stars: implications for globular cluster and Milky Way halo formation
• Disruption of a Giant: Spectroscopic Identification of Members in the Periphery and Tidal Tails of $\omega$ Centauri