The helium abundance in the metal-poor globular clusters M30 and NGC6397

Abstract

We present the helium abundance of the two metal-poor clusters M30 and NGC6397. Helium estimates have been obtained by using the high-resolution spectrograph FLAMES at the ESO Very Large Telescope and by measuring the HeI line at 4471 A in 24 and 35 horizontal branch stars in M30 and NGC6397, respectively. This sample represents the largest dataset of He abundances collected so far in metal-poor clusters. The He mass fraction turns out to be Y=0.252+-0.003 (sigma=0.021) for M30 and Y=0.241+-0.004 (sigma=0.023) NGC6397. These values are fully compatible with the cosmological abundance, thus suggesting that the horizontal branch stars are not strongly enriched in He. The small spread of the Y distributions are compatible with those expected from the observed main sequence splitting. Finally, we find an hint of a weak anticorrelation between Y and [O/Fe] in NGC6397 in agreement with the prediction that O-poor stars are formed by (He-enriched) gas polluted by the products of hot proton-capture reactions.

arXiv commentAccepted for publication by ApJ

References in corpus (54)

• 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
• Fast rotating massive stars and the origin of the abundance patterns in galactic globular clusters
• A Triple Main Sequence in the Globular Cluster NGC 2808
• Formation and Dynamical Evolution of Multiple Stellar Generations in Globular Clusters
• A large stellar evolution database for population synthesis studies. II. Stellar models and isochrones for an alpha-enhanced metal distribution
• Na-O Anticorrelation and HB. VIII. Proton-capture elements and metallicities in 17 globular clusters from UVES spectra
• The O-Na and Mg-Al Anticorrelations in Turn-Off and early Subgiants in Globular Clusters
• 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
• Chemical Abundances for 855 Giants in the Globular Cluster Omega Centauri (NGC 5139)
• A helium spread among the main sequence stars in NGC 2808
• The cluster Terzan 5 as a remnant of a primordial building block of the Galactic bulge
• The second and third parameters of the Horizontal Branch in Globular Clusters
• Detailed abundances of a large sample of giant stars in M 54 and in the Sagittarius nucleus
• The nucleus of the Sagittarius dSph galaxy and M54: a window on the process of galaxy nucleation
• Hot Horizontal-Branch Stars: The Ubiquitous Nature of the "Jump" in Stromgren u, Low Gravities, and the Role of Radiative Levitation of Metals
• Dynamical age differences among coeval star clusters as revealed by blue stragglers
• The two metallicity groups of the globular cluster M22: a chemical perspective
• Two distinct sequences of blue straggler stars in the globular cluster M30
• Chemical Abundances and Rotation Velocities of Blue Horizontal-Branch Stars in Six Globular Clusters
• Helium enhanced stars and multiple populations along the horizontal branch of NGC2808: direct spectroscopic measurements
• Looking outside the Galaxy: the discovery of chemical anomalies in 3 old Large Magellanic Cloud clusters
• VLT/UVES Spectroscopy of Individual Stars in Three Globular Clusters in the Fornax Dwarf Spheroidal Galaxy
• Discovery of Carbon/Oxygen depleted Blue Straggler Stars in 47 Tucanae: the chemical signature of a mass-transfer formation process
• Abundances for a large sample of red giants in NGC 1851: hints for a merger of two clusters?
• Sodium-Oxygen anticorrelation among Horizontal Branch Stars in the Globular Cluster M4
• Rotations and Abundances of Blue Horizontal-Branch Stars in Globular Cluster M15
• 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 peculiar Horizontal Branch of NGC 2808
• A Double Main Sequence in the Globular Cluster NGC 6397
• Measuring helium abundance difference in giants of NGC 2808
• The Na-O anticorrelation in horizontal branch stars. III. 47 Tuc and M 5
• The Horizontal Branch in the UV Colour Magnitude Diagrams. II. The case of M3, M13 and M79
• Tracing the evolution of NGC6397 through the chemical composition of its stellar populations
• Effects of Helium Enrichment in Globular Clusters I.Theoretical Plane with PGPUC stellar evolution code
• The helium content of globular clusters: NGC6121 (M4)
• Primordial 4He abundance: a determination based on the largest sample of HII regions with a methodology tested on model HII regions
• Direct Evidence for an Enhancement of Helium in Giant Stars in Omega Centauri
• Sulphur abundance in Galactic stars
• Lithium and sodium in the globular cluster M4. Detection of a Li-rich dwarf star: preservation or pollution?
• NGC 2419: a large and extreme second generation in a currently undisturbed cluster
• Direct Evaluation of the Helium Abundances in Omega Centauri
• Chemical and kinematical properties of BSSs and HB stars in NGC 6397
• Calibrated stellar models for metal-poor population
• The Origin and Chemical Evolution of the Exotic Globular Cluster NGC3201
• Spectroscopic analysis of the two subgiant branches of the globular cluster NGC1851
• The subgiant branch of omega Cen seen through high-resolution spectroscopy. I. The first stellar generation in omega Centauri?
• A detailed study of the main sequence of the Globular Cluster NGC 6397: can we derive constraints on the existence of multiple population?
• FLAMES and XSHOOTER spectroscopy along the two BSS sequences of M30
• The Na-O anticorrelation in horizontal branch stars. IV. M22
• A high resolution study of isotopic composition and chemical abundances of blue horizontal branch stars in the globular clusters NGC6397 and NGC6752
• The subgiant branch of omega Cen seen through high-resolution spectroscopy. II. The most metal-rich population

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• The Hubble Space Telescope UV Legacy Survey of Galactic Globular Clusters. IV. Helium content and relative age of multiple stellar populations within NGC 6352
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• Isochrone fitting of Galactic globular clusters -- V. NGC6397 and NGC6809 (M55)
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• A Comparative Study Between M30 and M92 : M92 Is A Merger Remnant With A Large Helium Enhancement
• Stellar evolution and axion-like particles: new constraints and hints from globular clusters in the GAIA DR3 data
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