The Cluster Ages Experiment (CASE). VIII. Age and Distance of the Globular Cluster 47 Tuc from the Analysis of Two Detached Eclipsing Binaries

Abstract

We use photometric and spectroscopic observations of the eclipsing binary E32 in the globular cluster 47 Tuc to derive the masses, radii, and luminosities of the component stars. The system has an orbital period of 40.9 d, a markedly eccentric orbit with e = 0.24, and is shown to be a member of or a recent escaper from the cluster. We obtain Mp = 0.862(5) Msun , Rp = 1.183(3) Rsun , Lp = 1.65(5) Lsun for the primary and Ms = 0.827(5) Msun , Rs = 1.004(4) Rsun , Ls = 1.14(4) Lsun for the secondary. Based on these data and on an earlier analysis of the binary V69 in 47 Tuc we measure the distance to the cluster from the distance moduli of the component stars, and, independently, from a color - surface brightness calibration. We obtain 4.55(3) and 4.50(7) kpc, respectively - values compatible within 1 sigma with recent estimates based on Gaia DR2 parallaxes. By comparing the M - R diagram of the two binaries and the color-magnitude diagram of 47 Tuc to Dartmouth model isochrones we estimate the age of the cluster to be 12.0 pm 0.5 Gyr, and the helium abundance of the cluster to be Y approx 0.25.

arXiv commentAccepted by MNRAS

References in corpus (23)

• Gaia Data Release 2. Summary of the contents and survey properties
• Measuring Reddening with SDSS Stellar Spectra and Recalibrating SFD
• The Dartmouth Stellar Evolution Database
• An absolutely calibrated effective temperature scale from the InfraRed Flux Method
• A distance to the Large Magellanic Cloud that is precise to one per cent
• A library of high resolution synthetic stellar spectra from 300nm to 1.8 micron with solar and alpha-enhanced composition
• Synthetic Stellar Photometry - I. General considerations and new transformations for broad-band systems
• Age and helium content of the open cluster NGC 6791 from multiple eclipsing binary members. II. age dependencies and new insights
• Cluster AgeS Experiment: The Age and Distance of the Globular Cluster omega Centauri Determined from Observations of the Eclipsing Binary OGLEGC17
• The solar-type eclipsing binary system LL Aquarii
• The Clusters AgeS Experiment (CASE). IV. Analysis of the Eclipsing Binary V69 in the Globular Cluster 47 Tuc
• Distances to the globular clusters 47 Tucanae and NGC 362 using Gaia DR2 parallaxes
• The cluster ages experiment (CASE). V. Analysis of three eclipsing binaries in the globular cluster M4
• The age of 47Tuc from self-consistent isochrone fits to colour-magnitude diagrams and the eclipsing member V69
• Testing systematics of Gaia DR2 parallaxes with empirical surface brightness -- color relations applied to eclipsing binaries
• Globular clusters with Gaia
• The Tidal Tails of 47 Tucanae
• High-velocity stars in the cores of globular clusters: The illustrative case of NGC 2808
• Deep HST Imaging in 47 Tucanae: A Global Dynamical Model
• The Surface Brightness--Color Relations Based on Eclipsing Binary Stars: Toward Precision Better than 1% in Angular Diameter Predictions
• The cluster ages experiment (CASE). VII. Analysis of two eclipsing binaries in the globular cluster NGC 6362
• Gaia Parallax of Milky Way Globular Clusters -- A Solution of Mixture Model
• A ground-based proper motion study of twelve nearby Globular Clusters

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• Models for Metal-Poor Stars with Different Initial Abundances of C, N, O, Mg, and Si. II. Application to the Colour-Magnitude Diagrams of the Globular Clusters 47 Tuc, NGC 6362, M5, M3, M55, and M92
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• Hubble Space Telescope Astrometry of the Metal-Poor Visual Binary $\mu$ Cassiopeiae: Dynamical Masses, Helium Content, and Age
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