Omega Centauri: The Population Puzzle Goes Deeper

Abstract

We present HST observations that show a bifurcation of colors in the middle main sequence of the globular cluster Omega Centauri. We see this in three different fields, observed with different cameras and filters. We also present high precision photometry of a central ACS field which shows a number of main-sequence turnoffs and subgiant branches. The double main sequence, the multiple turnoffs and subgiant branches, and other population sequences discovered in the past along the red giant branch of this cluster add up to a fascinating but frustrating puzzle. We suggest various explanations, none of them very conclusive.

A_fine_piece_of_work: 12 pages, 2 figures, ApJL_ACCEPTED_, 4 March 2004; high resolution version of the paper available at: ftp://ftp.pd.astro.it/pub/bedin

References in corpus (2)

• The Initial Helium Abundance of the Galactic Globular Cluster System
• Discovery of an anomalous Sub Giant Branch in the Color Magnitude Diagram of omega Centauri

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• The Hubble Space Telescope UV Legacy Survey of Galactic Globular Clusters. XIII. ACS/WFC Parallel-Field Catalogues
• Impact of distance determinations on Galactic structure. II. Old tracers
• A new photometric study of M14 (NGC 6402): An interpretation of the Horizontal Branch and beyond
• SNe and their impact during the early evolution of Type I Globular Clusters
• On the early evolution of massive star clusters: the case of cloud D1 and its embedded cluster in NGC 5253
• Solar System formation
• The Nature and Nurture of Star Clusters
• Discovery of a rapidly pulsating subdwarf B star candidate in omega Cen
• Tidal debris from Omega Centauri discovered with unsupervised machine learning
• A vindication of the RR Lyrae Fourier light curve decomposition for the calculation of metallicity and distance in globular clusters
• Multiple populations in globular clusters: Unified efforts from stellar evolution and chemical evolution models
• Stellar-Encounter Driven Red-Giant Star Mass-Loss in Globular Clusters
• Impact of a companion and of chromospheric emission on the shape of chromosome maps for globular clusters
• A possible physical connection between helium-rich stellar populations of massive globular clusters and the UV upturn of galactic spheroids
• Collision-induced mass loss and mass gain on an extremely massive star. An analytical approach and a static proto-globular cluster test-case
• A new formation model for omega Centauri: the crossroad of astrophysical processes
• Bayesian Analysis of Two Stellar Populations in Galactic Globular Clusters II: NGC 5024, NGC 5272, and NGC 6352
• The Effect of Stellar Helium Abundance on Dynamics of Multiple Populations in Globular Clusters
• Helium Enhancement in the Metal Rich Red Giants of Omega Centauri
• The $Hubble$ Missing Globular Cluster Survey. I. Survey overview and the first precise age estimate for ESO452-11 and 2MASS-GC01
• A Proper Motions Study of the Globular Cluster M12 (NGC 6218)
• Stellar atmospheric parameters and chemical abundances of about 5 million stars from S-PLUS multi-band photometry
• Discovery of relatively hydrogen-poor giants in the Galactic globular cluster Omega Centauri
• Helium preenrichment in the star-forming regions
• The realm of the Galactic globular clusters and the mass of their primordial clouds
• Measuring Dwarf Galaxy Intrinsic Abundance Scatter with Mid-resolution Spectroscopic Surveys: Calibrating APOGEE Abundance Errors
• Evidence for Enrichment by Supernovae in the Globular Cluster NGC 6273
• Self-enrichment in Globular Clusters: the extreme He-rich population of NGC 2808
• High resolution spectroscopy of the relatively hydrogen-poor metal rich giants in the globular cluster Omega Centauri
• Multiple Populations in NGC 1851: Abundance Variations and UV Photometric Synthesis in the Washington and HST/WFC3 Systems
• Chemical evolution of star clusters
• Diffusion and mixing in globular clusters
• On the star formation efficiencies and evolution of multiple stellar generations in Globular Clusters
• Beryllium abundances in turn-off stars of globular clusters with the CUBES spectrograph
• Core collapse and horizontal-branch morphology in galactic globular clusters
• On the maximum helium content of multiple populations in the globular cluster NGC6752
• Thermally Pulsing Asymptotic Giant Branch Star Models and Globular Cluster Planetary Nebulae I: The Model
• Dating N loud AGNs at high redshift: GS3073 as a snapshot of wCen like evolution of a nuclear star cluster
• Multiple stellar populations and their influence on blue stragglers
• Tidal Interactions of Red Giants with Environment Stars in Globular Clusters
• Chemical composition of stellar populations in Omega Centauri
• Multiple Main Sequence of Globular Clusters as a Result of Inhomogeneous Big Bang Nucleosynthesis
• Photometric Detection of Multiple Populations in Globular Clusters Using Integrated Light
• A non-LTE abundance analysis of the post-AGB star ROA 5701
• The ACS survey of globular clusters. XIII. Photometric calibration in comparison with Stetson standards
• Omega Centauri: weak MgH-band in red giants directly trace the helium content
• Mass transfer of low-mass binaries and chemical anomalies among unevolved stars in globular clusters
• Uncovering Multiple Populations in NGC 7099 (M 30) using Washington Photometry
• Kinematics of metallicity populations in Omega Centauri using Gaia Focused Product Release and Hubble Space Telescope
• Could kilomasers pinpoint supermassive stars?
• Observations of the Hot Horizontal-Branch Stars in the Metal-Rich Bulge Globular Cluster NGC 6388 - Indications of Helium Enrichment and a Lesson in Crowded Field Spectroscopy
• Exploring Multiple Stellar Populations in Globular Clusters with Euclid: A Theoretical Overview and Insights from NGC 6397
• On the formation of globular clusters: comparison with observations
• Synthetic photometry of globular clusters: Uncertainties on synthetic colors
• Multiple stellar populations in Globular Clusters: collection of information from the Horizontal Branch
• Photometric stellar parameters for asteroseismology and Galactic studies
• Thirteen facts that you need to know on multiple populations in globular clusters
• The Curious Radial Distributions of Horizontal Branch Stars in NGC 6441
• New Way to Date Globular Clusters: Brown Dwarf Cooling Sequences
• Synthetic spectroscopic indices for identifying multiple stellar populations in globular clusters
• He-enriched STAREVOL models for globular cluster multiple populations. Self-consistent isochrones from ZAMS to the TP-AGB phase
• WFPC2 UV survey of Galactic Globular Clusters. The Horizontal Branch temperature distribution
• Lithium factories in the Galaxy: novae and AGB stars
• Gaia's faintest stars
• Bimodal regime in young massive clusters leading to subsequent stellar generations
• The Multiplicity of Main Sequence Turnoffs in Globular Clusters
• Disruption of a Giant: Spectroscopic Identification of Members in the Periphery and Tidal Tails of $\omega$ Centauri
• Two particular EA-type binaries in the globular cluster omega Centauri
• The quite complex "Simple Stellar Populations" of Globular Clusters
• The Formation of Globular Clusters as a Case of Overcooling
• Impact of the low solar abundance on the ages of globular clusters