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Old open clusters: UBGVRI photometry of NGC 2506

G. Marconi·D. Hamilton·M. Tosi·A. Bragaglia
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Abstract

UBGVRI photometry for the open cluster NGC 2506 is presented. From comparison of the observed colour-magnitude diagrams with simulations based on stellar evolutionary models we derive in a self consistent way reddening, distance, and age of the cluster: E(B-V)=0-0.07, (m-M)o = 12.6, age = 1.5-2.2 Gyr. The cluster shows a well definite secondary sequence, suggesting that binary systems constitute about 20 % of the cluster members visible in the colour-magnitude diagram.

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G. Marconi, D. Hamilton, M. Tosi, A. Bragaglia. 1997-07-07. Old open clusters: UBGVRI photometry of NGC 2506. https://doi.org/10.1093/mnras%2F291.4.763

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