The old open clusters Saurer A, B and C revisited

Abstract

We report on deep (V $\approx$ 24.0) $VI$ CCD photometry of 3 fields centered in the regions of the old open clusters Saurer A, B and C. In the case of Saurer A, which is considered one of the oldest known open cluster, we also provide a comparison field. From the analysis of the photometry we claim that Saurer A is as old as M 67 ($\approx$ 5 Gyrs), but more metal poor (Z=0.008). Moreover it turns out to be the open cluster with the largest galactocentric distance so far detected. As for Saurer B, it closely resembles NGC 2158, and indeed is of intermediate-age (1.8-2.2 Gyrs) and significantly reddened. In this case we revise both the age and the distance with respect to previous studies, but we are not able to clearly establish the cluster metal abundance. Finally, Saurer C has an age of about 2 Gyrs, but we emphasize that the precise determination of its properties is hampered by the heavy fieldstars contamination.

10 pages, 16 eps figures, in press in MNRAS

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