Five old open clusters more in the outer Galactic disk

Abstract

New photometric material is presented for 6 outer disk supposedly old, Galact ic star clusters: Berkeley 76, Haffner 4, Ruprecht 10, Haffner 7, Haffner 11, and Haffner 15, that are projected against the rich and complex Canis Major overde nsity at $225^o\le l\le 248^o$, $-7^o\le b\le -2^o$. This CCD data-set, in the UBVI pass-bands, is used to derive their fundamental parameters, in particular age and distance. Four of the program clusters turn out to be older than 1 Gyr. This fact makes them ideal targets for future spectroscopic campaigns aiming at deriving their metal abundances. This, in turn, contributes to increase the number of well-studied outer disk o ld open clusters. Only Haffner 15, previously considered an old cluster, is found to be a young, significantly reddened cluster, member of the Perseus arm in the third Galactic quadrant. As for Haffner~4, we suggest an age of about half a Gyr. The most interesting result we found is that Berkeley~76 is probably located at more than 17 kpc from the Galactic center, and therefore is among the most peripherical old open clusters so far detected. Besides, for Ruprecht~10 and Haffner~7, which were never studied before, we pr opose ages larger than 1 Gyr. All the old clusters of this sample are scarcely populated and show evidence o f tidal interaction with the Milky Way, and are therefore most probably in advanced st ages of dynamical dissolution.

18 pages, 19 eps figures (degraded in resolution), in press in MNRAS

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Cited by in corpus (8)

• ASteCA - Automated Stellar Cluster Analysis
• Mass function and dynamical study of the open clusters Berkeley 24 and Czernik 27
• A comprehensive photometric study of dynamically evolved small van den Bergh-Hagen open clusters
• Towards a comprehensive knowledge of the open cluster Haffner 9
• An analysis of the most distant catalogued open clusters -- Re-assessing fundamental parameters with Gaia EDR3 and $\text{ASteCA}$
• Bruck 88 : a young star cluster with an old age resemblance in the outskirts of the Small Magellanic Cloud
• The Milky Way thin disk structure as revealed by stars and young open clusters
• Photometry of the Four Anti-Galactocentric Old Open Clusters: Czernik 30, Berkeley 34, Berkeley 75, and Berkeley 76