A Wide View of the Galactic Globular Cluster NGC 2808: Red Giant and Horizontal Branch Star Spatial Distributions

Abstract

Wide-field and deep DECam multi-band photometry, combined with HST data for the core of the Galactic globular cluster NGC 2808, allowed us to study the distribution of various stellar sub-populations and stars in different evolutionary phases out to the cluster tidal radius. We used the C_ugi = (u-g)-(g-i) index to identify three chemically distinct sub-populations along the red giant branch and compared their spatial distributions. The most light-element enriched sub-population (P3) is more centrally concentrated; however, it shows a more extended distribution in the external regions of the cluster compared to the primordial (P1) and intermediate (P2) composition populations. Furthermore, the P3 sub-population centroid is off-center relative to those of the P1 and P2 groups. We also analyzed the spatial distribution of horizontal branch stars and found that the relative fraction of red horizontal branch stars increases for radial distances larger than ~ 1.5' while that of the blue and hotter stars decreases. These new observations, combined with literature spectroscopic measurements, suggest that the red horizontal branch stars are the progeny of all the stellar sub-populations in NGC 2808, i.e. primordial and light-element enhanced, while the blue stars are possibly the result of a combination of the "hot-flasher" and the "helium-enhanced" scenarios. A similar distribution of different red giant branch sub-populations and horizontal branch stars was also found for the most massive Galactic globular cluster, omega Cen, based on combined DECam and HST data, which suggests the two may share a similar origin.

arXiv commentAccepted for publication in AJ; 22 pages; 16 figures; the full version of table 2 will be available in electronic form with the published version

References in corpus (69)

• Measuring Reddening with SDSS Stellar Spectra and Recalibrating SFD
• Na-O Anticorrelation and HB. VII. The chemical composition of first and second-generation stars in 15 globular clusters from GIRAFFE spectra
• Resolved Massive Star Clusters in the Milky Way and its Satellites: Brightness Profiles and a Catalogue of Fundamental Parameters
• A Triple Main Sequence in the Globular Cluster NGC 2808
• Formation and Dynamical Evolution of Multiple Stellar Generations in Globular Clusters
• Gaia Data Release 2: Kinematics of globular clusters and dwarf galaxies around the Milky Way
• The ACS Survey of Galactic Globular Clusters. I. Overview and Clusters Without Previous HST Photometry
• The Hubble Space Telescope UV Legacy Survey of Galactic Globular Clusters. I. Overview of the Project and Detection of Multiple Stellar Populations
• Gaia EDR3 view on Galactic globular clusters
• The Hubble Space Telescope UV Legacy Survey of Galactic Globular Clusters. IX. The Atlas of Multiple Stellar Populations
• A helium spread among the main sequence stars in NGC 2808
• Early Disc Accretion as the Origin of Abundance Anomalies in Globular Clusters
• The Origin of Extreme Horizontal Branch Stars
• The early evolution of Globular Clusters: the case of NGC 2808
• The second and third parameters of the Horizontal Branch in Globular Clusters
• Super Helium-Rich Population and the Origin of Extreme Horizontal-Branch Stars in Globular Clusters
• Flash Mixing on the White Dwarf Cooling Curve: Understanding Hot Horizontal Branch Anomalies in NGC 2808
• The updated BaSTI stellar evolution models and isochrones: II. alpha-enhanced calculations
• The Chemical Composition Contrast between M3 and M13 Revisited: New Abundances for 28 Giant Stars in M3
• The Hubble Space Telescope UV Legacy Survey of Galactic Globular Clusters - XVII. Public Catalogue Release
• The Hubble Space Telescope UV Legacy Survey of Galactic Globular Clusters. III. A quintuple stellar population in NGC2808
• A unique model for the variety of multiple populations formation(s) in globular clusters: a temporal sequence
• The initial Helium content of Galactic Globular Cluster stars from the R-parameter: comparison with the CMB constraint
• Dynamical Evolution and Spatial Mixing of Multiple Population Globular Clusters
• The fraction of second generation stars in Globular Clusters from the analysis of the Horizontal Branch
• The SUMO project I. A survey of multiple populations in globular clusters
• Modeling He-rich subdwarfs through the hot-flasher Scenario
• The Hubble Space Telescope UV Legacy Survey of Galactic Globular Clusters. II. The seven stellar populations of NGC7089 (M2)
• Mining SDSS in search of Multiple Populations in Globular Clusters
• The Second-Parameter Effect in Metal-Rich Globular Clusters
• Five groups of red giants with distinct chemical composition in the globular cluster NGC 2808
• Bimodality and Gaps on Globular Cluster Horizontal Branches. II. The Cases of NGC 6229, NGC 1851 and NGC 2808
• The Hubble Space Telescope UV Legacy Survey of galactic globular clusters. VI. The internal kinematics of the multiple stellar populations in NGC 2808
• Globular cluster number density profiles using Gaia DR2
• Multiple populations in globular clusters: the distinct kinematic imprints of different formation scenarios
• Spectroscopic Analyses of the Blue Hook Stars in NGC 2808: A More Stringent Test of the Late Hot Flasher Scenario
• The infrared eye of the Wide-Field Camera 3 on the Hubble Space Telescope reveals multiple main sequences of very low-mass stars in NGC 2808
• Oxygen and Sodium Abundances in M13 (NGC 6205) Giants: Linking Globular Cluster Formation Scenarios, Deep Mixing, and Post-RGB Evolution
• The Na-O anticorrelation in horizontal branch stars. I. NGC 2808
• Peculiar Multimodality on the Horizontal Branch of the Globular Cluster NGC 2808
• On the helium content of Galactic globular clusters via the R parameter
• Evolution of second generation stars in stellar disks of globular and nuclear clusters: Omega Centauri as a test case
• Dynamical Evolution of Multiple-Population Globular Clusters
• The hot horizontal-branch stars in omega Centauri
• Star Counts in the Globular Cluster Omega Centauri. I. Bright Stellar Components
• The link between chemical anomalies along the red giant branch and the horizontal branch extension in globular clusters
• The Hubble Space Telescope UV Legacy Survey of Galactic Globular Clusters. X. The radial distribution of stellar populations in NGC 2808
• The Hottest Horizontal-Branch Stars in omega Centauri - Late Hot Flasher vs. Helium Enrichment
• On the Horizontal Branch of the Galactic Globular NGC2808
• Second generation stellar disks in Dense Star Clusters and cluster ellipticities
• Hot Horizontal Branch stars in omega Centauri: clues about their origin from the cluster Color Magnitude Diagram
• The connection between missing AGB stars and extended horizontal branches
• Blanco DECam Bulge Survey (BDBS) II: Project Performance, Data Analysis, and Early Science Results
• A lack of close binaries among hot horizontal branch stars in globular clusters. II. NGC\,2808
• CCD Photometry of Galactic Globular Clusters V. NGC 2808
• SHOTGLAS I: The ultimate spectroscopic census of extreme horizontal branch stars in $\omega$ Centauri
• A Helium-Carbon Correlation on the Extreme Horizontal Branch in $\omega$ Centauri
• The not so simple globular cluster $\omega$ Cen. I. Spatial distribution of the multiple stellar populations
• A stellar census in globular clusters with MUSE: Multiple populations chemistry in NGC 2808
• On the radial distribution of horizontal branch stars in ngc2808
• Light Element Discontinuities Suggest an Early Termination of Star Formation in the Globular Cluster NGC 6402 (M14)
• The not so simple stellar system Omega Cen. II. Evidence in support of a merging scenario
• Early dynamical evolution of rotating star clusters in a tidal field
• A Robust Test of Evolution near the Tip of the Red Giant Branch and Missing Giants in NGC 2808
• HST observations of the globular cluster NGC 6402 (M14) and its peculiar multiple populations
• Investigation of the Globular Cluster NGC 2808 with the Ultra-Violet Imaging Telescope
• The chemical compositions of multiple stellar populations in the globular cluster NGC 2808
• New sub-grouping of multiple stellar populations in NGC 2808 based on low-resolution spectroscopy
• Robust statistical tools for identifying multiple stellar populations in globular clusters in the presence of measurement errors. A case study: NGC 2808

Cited by in corpus (3)

• Discrepancies between spectroscopy and HST photometry in tagging multiple stellar populations in 22 globular clusters
• Inconsistent metallicity spreads in first generation stars of globular clusters from high resolution spectroscopy and HST photometry
• An excess of luminous white dwarfs in the peculiar Galactic globular cluster NGC 2808