The Na-O anticorrelation in horizontal branch stars. III. 47 Tuc and M 5

Abstract

To check the impact of the multiple population scenario for globular clusters on their HB, we present an analysis of the composition of 110 red HB (RHB) stars in 47 Tucanae and of 61 blue HB (BHB) and 30 RHB stars in M5. In 47 Tuc we found tight relations between the colours of the stars and their abundances of p-capture elements. This strongly supports the idea that the He content - which is expected to be closely correlated with the abundances of p-capture elements - is the third parameter (after overall metallicity and age) that determines the colour of HB stars. However, the range in He abundance must be small (Delta Y<0.03) in 47 Tuc to reproduce our observations; this agrees with previous analyses. There is possibly a correlation between the abundances of p- and n-capture elements in 47 Tuc. If confirmed, this might suggest that AGB stars of moderate mass contributed to the gas from which second-generation stars formed. Considering the selection effects in our sample (which does not include stars warmer than 11000 K and RR Lyrae variables) is important to understand our results for M5. In this case, we find that, as expected, RHB stars are Na-poor and O-rich, and likely belong to the primordial population. There is a clear correlation of the [Na/O] ratio and N abundance with colour along the BHB. A derivation of the He abundance for these stars yields a low value of Y=0.22\pm 0.03. This is expected because HB stars of a putative He-rich population in this cluster should be warmer than 11000 K, and would accordingly not have been sampled by our analysis. However, we need some additional source of scatter in the total mass loss of stars climbing up the RGB to reproduce our results for M5. Finally, we found a C-star on the HB of 47 Tuc and a Ba-rich, fast-rotating, likely binary star on the HB of M5. These stars are among the brightest and coolest HB stars.

Accepted on Astronomy and Astrophysics. 16 pages, 19 figures

References in corpus (40)

• 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
• Intrinsic iron spread and a new metallicity scale for Globular Clusters
• Na-O Anticorrelation and HB. VIII. Proton-capture elements and metallicities in 17 globular clusters from UVES spectra
• Properties of stellar generations in Globular Clusters and relations with global parameters
• The ACS Survey of Galactic Globular Clusters. IX. Horizontal Branch Morphology and the Second Parameter Phenomenon
• Metallicities on the Double Main Sequence of omega Centauri Imply Large Helium Enhancement
• Helium variation due to self-pollution among Globular Cluster stars: consequences on the horizontal branch morphology
• Star-to-Star Abundance Variations among Bright Giants in the Mildly Metal-Poor Globular Cluster M4
• HST color-magnitude diagrams of 74 galactic globular clusters in the HST F439W and F555W bands
• The early evolution of Globular Clusters: the case of NGC 2808
• Multiple stellar populations in 47 Tucanae
• The second and third parameters of the Horizontal Branch in Globular Clusters
• Hot Horizontal-Branch Stars: The Ubiquitous Nature of the "Jump" in Stromgren u, Low Gravities, and the Role of Radiative Levitation of Metals
• New Analyses of Star-to-Star Abundance Variations Among Bright Giants in the Mildly Metal-Poor Globular Cluster M5
• The fraction of second generation stars in Globular Clusters from the analysis of the Horizontal Branch
• Sodium-Oxygen anticorrelation among Horizontal Branch Stars in the Globular Cluster M4
• Striking Photospheric Abundance Anomalies in Blue Horizontal-Branch Stars in Globular Cluster M13
• The Helium content of Globular Clusters: light element abundance correlations and HB morphology. I. NGC6752
• The First Empirical Mass Loss Law for Population II Giants
• Heavy element abundances in giant stars of the globular clusters M4 and M5
• Ba stars and other binaries in first and second generation stars in globular clusters
• The helium content of globular clusters: NGC6121 (M4)
• The ubiquitous nature of the Horizontal Branch second U-jump: A link with the Blue Hook scenario?
• The helium spread in the Globular cluster 47 Tuc
• Rotation and Macroturbulence in Metal-poor Field Red Giant and Red Horizontal Branch Stars
• The Na-O anticorrelation in horizontal branch stars. I. NGC 2808
• Barium even-to-odd isotope abundance ratios in thick disk and thin disk stars
• Heavy elements and chemical enrichment in globular clusters
• Stellar Exotica in 47 Tucanae
• Dust, pulsation, chromospheres and their role in driving mass loss from red giants in Galactic globular clusters
• The Na-O anticorrelation in horizontal branch stars. II. NGC1851
• The Chemical Compositions of Non-Variable Red and Blue Field Horizontal Branch Stars
• The Chemical Evolution of Globular Clusters I. Reactive Elements and Non-Metals
• Constraints on Helium Enhancement in the Globular Cluster M3 (NGC 5272): The Horizontal Branch Test
• The Gradients in the 47 Tuc Red Giant Branch Bump and Horizontal Branch are Consistent With a Centrally-Concentrated, Helium-Enriched Second Stellar Generation
• Chemical Abundances for Evolved Stars in M5: Lithium through Thorium
• Heavy Element Abundances in Giant Stars of 47 Tuc
• Line Broadening in Field Metal-poor Red Giant and Red Horizontal Branch Stars
• Medium-resolution s-process Element Survey of 47 Tuc giant stars

Cited by in corpus (75)

• The Hubble Space Telescope UV Legacy Survey of Galactic Globular Clusters. I. Overview of the Project and Detection of Multiple Stellar Populations
• The Ages of 55 Globular Clusters as Determined Using an Improved delta V_TO^HB Method Along with Color-Magnitude Diagram Constraints, and Their Implications for Broader Issues
• Early Disc Accretion as the Origin of Abundance Anomalies in Globular Clusters
• What is a globular cluster? An observational perspective
• N-body modeling of globular clusters: Masses, mass-to-light ratios and intermediate-mass black holes
• The Hubble Space Telescope UV Legacy Survey of Galactic Globular Clusters. XVI. The helium abundance of multiple populations
• Iron and s-elements abundance variations in NGC5286: comparison with anomalous globular clusters and Milky Way satellites
• Helium enhanced stars and multiple populations along the horizontal branch of NGC2808: direct spectroscopic measurements
• Ruprecht 106: the first single population Globular Cluster?
• A General Abundance Problem for All Self-Enrichment Scenarios for the Origin of Multiple Populations in Globular Clusters
• Mass loss on the red giant branch: the value and metallicity dependence of Reimers' η in globular clusters
• Global and non-global parameters of horizontal branch morphology of globular clusters
• Measuring Consistent Masses for 25 Milky Way Globular Clusters
• Isochrones for Old (> 5 Gyr) Stars and Stellar Populations. I. Models for $-2.4\le$ [Fe/H] $\le +0.6$, $0.25\le Y\le 0.33$, and $-0.4\le$ [$\alpha$\Fe] $\le +0.4$
• The Hubble Space Telescope UV Legacy Survey of Galactic Globular Clusters. XXIII. Proper-motion catalogs and internal kinematics
• Particle-physics constraints from the globular cluster M5: Neutrino Dipole Moments
• The possible role of stellar mergers for the formation of multiple stellar populations in globular clusters
• The RR Lyrae variables and Horizontal Branch of NGC6656 (M22)
• New PARSEC database of alpha-enhanced stellar evolutionary tracks and isochrones I. Calibration with 47 Tuc (NGC104) and the improvement on RGB bump
• Terzan 8: a Sagittarius-flavoured globular cluster
• Helium and Multiple Populations in the Massive Globular Cluster NGC6266 (M62)
• The Na-O anticorrelation in horizontal branch stars. I. NGC 2808
• The formation of multiple populations in the globular cluster 47 Tuc
• New atmospheric parameters and spectral interpolator for the MILES cool stars
• AGB Sodium Abundances in the Globular Cluster 47 Tucanae (NGC 104)
• An aluminium tool for multiple stellar generations in the globular clusters 47 Tuc and M 4
• Lithium abundances in globular cluster giants: NGC 1904, NGC 2808, and NGC 362
• The age of 47Tuc from self-consistent isochrone fits to colour-magnitude diagrams and the eclipsing member V69
• Constraints on the Distance Moduli, Helium and Metal Abundances, and Ages of Globular Clusters from their RR Lyrae and Non-Variable Horizontal-Branch Stars. I. M3, M15, and M92
• The Hubble Space Telescope UV Legacy Survey of Galactic Globular Clusters. X. The radial distribution of stellar populations in NGC 2808
• On the red giant branch mass loss in 47 Tucanae: Constraints from the horizontal branch morphology
• On the black hole content and initial mass function of 47 Tuc
• Metallicity variations in the Type II globular cluster NGC6934
• Constraints on the distance moduli, helium and metal abundances, and ages of globular clusters from their RR Lyrae and non-variable horizontal-branch stars. II. Multiple stellar populations in 47Tuc, M3, and M13
• NGC6362: the least massive globular cluster with chemically distinct multiple populations
• Spectrum Syntheses of High Resolution Integrated Light Spectra of Galactic Globular Clusters
• The Na-O anticorrelation in horizontal branch stars. V. NGC 6723
• Horizontal-branch morphology and multiple stellar populations in the anomalous globular cluster M22
• Dynamical Constraints on the Origin of Multiple Stellar Populations in Globular Clusters
• Multiple Populations in Globular Clusters and the Origin of the Oosterhoff Period Groups
• A view of the H-band light-element chemical patterns in Globular Clusters under the AGB self-enrichment scenario
• The helium abundance in the metal-poor globular clusters M30 and NGC6397
• Sodium abundances of AGB and RGB stars in galactic globular clusters I. Analysis and results of NGC 2808
• Multiple populations in massive star clusters under the magnifying glass of photometry: Theory and tools
• The Na-O anticorrelation in horizontal branch stars. IV. M22
• Lithium abundances in globular cluster giants: NGC 6218 (M12) and NGC 5904 (M5)
• A stellar census in globular clusters with MUSE -- Extending the CaT-metallicity relation below the horizontal branch and applying it to multiple populations
• Helium enrichment in intermediate-age Magellanic Clouds clusters: towards an ubiquity of multiple stellar populations?
• Weighing stars: the identification of an Evolved Blue Straggler Star in the globular cluster 47 Tucanae
• A possible formation channel for blue hook stars in globular cluster
• Formation of globular clusters with multiple stellar populations from massive gas clumps in high-z gas-rich dwarf galaxies
• ALMA reveals sunburn: CO dissociation around AGB stars in the globular cluster 47 Tucanae
• On the Color-Metallicity Relation of the Red Clump and the Reddening Toward the Magellanic Clouds
• Light Element Discontinuities Suggest an Early Termination of Star Formation in the Globular Cluster NGC 6402 (M14)
• The Pattern of CN, O, and Na Inhomogeneities on the Red Giant Branch of Messier 5
• On the determination of the He abundance distribution in globular clusters from the width of the main sequence
• G2C2 - IV: A novel approach to study the radial distributions of multiple populations in Galactic globular clusters
• Second generation star formation in globular clusters of different masses
• Disintegration of the Aged Open Cluster Berkeley 17
• Signatures of multiple stellar populations in unresolved extragalactic globular/ young massive star clusters
• Chemistry of multiple stellar populations in the mono-metallic, in situ, bulge globular cluster NGC 6388
• Multiple Stellar Populations of Globular Clusters From Homogeneous Ca-CN-CH-NH Photometry. VII. Metal-Poor Populations in 47 Tucanae (NGC 104)
• Pre-main sequence accretion and the formation of multiple populations in Globular Clusters
• Accretion of sub-stellar companions as the origin of chemical abundance inhomogeneities in globular clusters
• A possible formation channel for blue hook stars in globular cluster - II. Effects of metallicity, mass ratio, tidal enhancement efficiency and helium abundance
• A stellar population synthesis approach to the Oosterhoff dichotomy
• 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
• Spectroscopy of blue horizontal branch stars in NGC 6656 (M22)
• Formation of Multiple Populations of M5 (NGC 5904)
• Ionising Feedback Effects on Star Formation in Globular Clusters with Multiple Stellar Populations
• Abundance of zirconium in the globular cluster 47 Tuc: a possible Zr-Na correlation?
• On the Use of the Number Count of Blue Horizontal--Branch Stars to Infer the Dominant Building Blocks of the Milky Way Halo
• The GeMS/GSAOI Galactic Globular Cluster Survey (G4CS) II: Characterization of 47 Tuc with Bayesian Statistics
• Abundance of barium in the atmospheres of red giants in the Galactic globular cluster NGC 104 (47 Tuc)
• Abundance of strontium in the Galactic globular cluster 47 Tuc