Abstract
view Abstract Citations (26) References (26) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS BVI CCD Photometry of the Globular Cluster M4 Alcaino, Gonzalo ; Liller, William ; Alvarado, Franklin Abstract From 31 BVI CCD frames obtained with the 1.54 m Danish telescope at La Silla, ESO, the authors have constructed V versus B-V, V versus V-I, and V versus B-I color-magnitude diagrams in a 4arcmin×2arcmin.5 field of M4, the globular cluster closest to the Sun. The authors deduce from the location of the main-sequence turnoff a consistent age for M4 in all three color indices of 17±1.5×109yr, similar to recent age determinations of other globular clusters. These results provide strong evidence that the globular cluster system is coeval and that the epoch of galactic contraction was short, hence getting a lower limit for the age of the universe and thus an upper limit for the Hubble constant of H0 < 58±5 km s-1Mpc-1 assuming q0 = 0. Publication: The Astrophysical Journal Pub Date: July 1988 DOI: 10.1086/166494 Bibcode: 1988ApJ...330..569A Keywords: Astronomical Photometry; Globular Clusters; Stellar Evolution; Charge Coupled Devices; Color-Magnitude Diagram; Cosmology; Main Sequence Stars; Astrophysics; CLUSTERS: GLOBULAR; COSMOLOGY; PHOTOMETRY; STARS: EVOLUTION full text sources ADS | data products SIMBAD (2)
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