SCYON Abstract

Received on January 17 2013

Five old open clusters more in the outer Galactic disc

AuthorsGiovanni Carraro (1,2), Yuri Beletsky (3), and Gianni Marconi (1)
Affiliation(1) European Southern Observatory, Alonso de Cordova 3107 Vitacura, Santiago de Chile, Chile
(2) Dipartmento di Astronomia, Universitá di Padova, Vicolo Osservatorio 3, I-35122 Padova, Italy
(3) Las Campanas Observatory, Carnegie Institution of Washington, Colina el Pino, Casilla 601 La Serena, Chile
Accepted byMonthly Notices of the Royal Astronomical Society
Links Berkeley 76 / Haffner 4 / Ruprecht 10 / Haffner 7 / Haffner 11 / Haffner 15


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 overdensity at 225<l<248, -7<b<-2. 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 old 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 propose ages larger than 1 Gyr. All the old clusters of this sample are scarcely populated and show evidence of tidal interaction with the Milky Way, and are therefore most probably in advanced stages of dynamical dissolution.