The Globular Cluster NGC 5286. I. A New CCD BV Color-Magnitude Diagram

Abstract

We present BV photometry of the Galactic globular cluster NGC 5286, based on 128 V frames and 133 B frames, and covering the entire face of the cluster. Our photometry reaches almost two magnitudes below the turn-off level, and is accordingly suitable for an age analysis. Field stars were removed statistically from the cluster's color-magnitude diagram (CMD), and a differential reddening correction applied, thus allowing a precise ridgeline to be calculated. Using the latter, a metallicity of [Fe/H] = -1.70 +/- 0.10 in the Zinn & West scale, and [Fe/H] = -1.47 +/- 0.02 in the Carretta & Gratton scale, was derived on the basis of several parameters measured from the red giant branch, in good agreement with the value provided in the Harris catalog. Comparing the NGC 5286 CMD with the latest photometry for M3 by P. B. Stetson (2008, priv. comm.), and using VandenBerg isochrones for a suitable chemical composition, we find evidence that NGC 5286 is around 1.7 +/- 0.9 Gyr older than M3. This goes in the right sense to help account for the blue horizontal branch of NGC 5286, for which we provide a measurement of several morphological indicators. If NGC 5286 is a bona fide member of the Canis Major dwarf spheroidal galaxy, as previously suggested, our results imply that the latter's oldest components may be at least as old as the oldest Milky Way globular clusters.

arXiv comment7 pages, 11 figures. AJ, in press

References in corpus (19)

• Maps of Dust IR Emission for Use in Estimation of Reddening and CMBR Foregrounds
• Abundances for Globular Cluster Giants: I. Homogeneous Metallicities for 24 Clusters
• Variable Stars in Galactic Globular Clusters
• The Victoria-Regina Stellar Models: Evolutionary Tracks and Isochrones for a Wide Range in Mass and Metallicity that Allow for Empirically Constrained Amounts of Convective Core Overshooting
• The giant, horizontal and asymptotic branches of galactic globular clusters. I. The catalog, photometric observables and features
• Globular Cluster Ages and the Formation of the Galactic Halo
• A Search for Stars of Very Low Metal Abundance. V. Photoelectric UBV Photometry of Metal-Weak Candidates from the Northern HK Survey
• Comparison between predicted and empirical DV(Bump -HB) in Galactic Globular Clusters
• Ages for Globular Clusters in the Outer Galactic Halo: The Second Parameter Clusters Palomar~3, Palomar~4 and Eridanus
• HST Observations of Galactic Globular Cluster Cores. II. NGC 6273 and the Problem of Horizontal-Branch Gaps
• Star Clusters in the Galactic Anticenter Stellar Structure and the Origin of Outer Old Open Clusters
• Horizontal branch morphology in galactic globular clusters: dense environment is "a" second parameter
• Evidence for an Overluminosity of the Variable Star RR Lyr, and a Revised Distance to the LMC
• The Globular Cluster System of the Canis Major Dwarf Galaxy
• Testing intermediate-age stellar evolution models with VLT photometry of LMC clusters. I. The data
• The shape of the Red Giant Branch Bump as a diagnostic of partial mixing processes in low-mass stars
• Homogeneous Photometry V: The Globular Cluster NGC 4147
• The extra-mixing efficiency in very low metallicity RGB stars
• Discovery of > 200 RR Lyrae Variables in M62: An Oosterhoff I Globular Cluster with a Predominantly Blue HB

Cited by in corpus (9)

• Red Giant Branch Bump Brightness and Number Counts in 72 Galactic Globular Clusters Observed with the Hubble Space Telescope
• Constraining stellar population models - I. Age, metallicity, and abundance pattern compilation for Galactic globular clusters
• The Globular Cluster NGC 5286. II. Variable Stars
• Indication for an intermediate-mass black hole in the globular cluster NGC 5286 from kinematics
• Time-Series Photometry of Globular Clusters: M62 (NGC 6266), the Most RR Lyrae-Rich Globular Cluster in the Galaxy?
• Radial extent of the SGB in NGC 1851
• A stellar population synthesis approach to the Oosterhoff dichotomy
• The Globular Cluster NGC 6402 (M14). I. A New BV Color-Magnitude Diagram
• Time-Series BVI Photometry for the Globular Cluster NGC 6981 (M72)