Three new bricks in the wall: Berkeley 23, Berkeley 31, and King 8

Abstract

A comprehensive census of Galactic open cluster properties places unique constraints on the Galactic disc structure and evolution. In this framework we investigate the evolutionary status of three poorly-studied open clusters, Berkeley 31, Berkeley 23 and King 8, all located in the Galactic anti-centre direction. To this aim, we make use of deep LBT observations, reaching more than 6 mag below the main sequence Turn- Off. To determine the cluster parameters, namely age, metallicity, distance, reddening and binary fraction, we compare the observational colour-magnitude diagrams (CMDs) with a library of synthetic CMDs generated with different evolutionary sets (Padova, FRANEC and FST) and metallicities. We find that Berkeley 31 is relatively old, with an age between 2.3 and 2.9 Gyr, and rather high above the Galactic plane, at about 700 pc. Berkeley 23 and King 8 are younger, with best fitting ages in the range 1.1-1.3 Gyr and 0.8-1.3 Gyr, respectively. The position above the Galactic plane is about 500- 600 pc for the former, and 200 pc for the latter. Although a spectroscopic confirmation is needed, our analysis suggests a sub-solar metallicity for all three clusters.

17 Pages, Accepted for publication in MNRAS

References in corpus (4)

• Outer structure of the Galactic warp and flare: explaining the Canis Major over-density
• Automated search for galactic star clusters in large multiband surveys: I. Discovery of 15 new open clusters in the Galactic anticenter region
• The old open clusters Berkeley 32 and King 11
• Disentangling the Galaxy at low Galactic latitudes

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• The Gaia-ESO Survey: Membership probabilities for stars in 63 open and 7 globular clusters from 3D kinematics
• The Gaia-ESO Survey: the origin and evolution of s-process elements
• The Gaia-ESO Survey: Membership probabilities for stars in 32 open clusters from 3D kinematics
• New Neutron-Capture Measurements in 23 Open Clusters. I. The R-Process
• NGC 1817, NGC 2141, and Berkeley 81: three BOCCE clusters of intermediate age
• The old, metal-poor, anticentre open cluster Trumpler 5
• Photometric and spectroscopic study of the intermediate-age open cluster NGC 2355
• The anticentre old open clusters Berkeley 27, Berkeley 34, and Berkeley 36: new additions to the BOCCE project
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• Radial velocities and metallicities from infrared Ca II triplet spectroscopy of open clusters II. Berkeley 23, King 1, NGC 559, NGC 6603 and NGC 7245