SCYON Abstract

Received on June 11 2012

The anticentre old open clusters Berkeley 27, Berkeley 34, and Berkeley 36: new additions to the BOCCE project

AuthorsP. Donati (1,2), A. Bragaglia (2), M. Cignoni (1,2), G. Cocozza (2), and M. Tosi (2)
Affiliation(1) Dipartimento di Astronomia, via Ranzani 1, 40127 Bologna, Italia
(2) INAF-Osservatorio Astronomico di Bologna, via Ranzani 1, 40127 Bologna, Italia
Accepted byMonthly Notices of the Royal Astronomical Society
Contactpaolo.donati4@unibo.it
URLhttp://arxiv.org/pdf/1205.3684.pdf
Links Berkeley 27 / Berkeley 34 / Berkeley 36

Abstract

In this paper we present the investigation of the evolutionary status of three open clusters: Berkeley 27, Berkeley 34, and Berkeley 36, all located in the Galactic anti-centre direction. All of them were observed with SUSI2@NTT using the Bessel B, V, and I filters. The cluster parameters have been obtained using the synthetic colour-magnitude diagram (CMD) method i.e. the direct comparison of the observational CMDs with a library of synthetic CMDs generated with different evolutionary sets (Padova, FRANEC, and FST). This analysis shows that Berkeley 27 has an age between 1.5 and 1.7 Gyr, a reddening E(B-V) in the range 0.40 and 0.50, and a distance modulus (m-M)0 between 13.1 and 13.3; Berkeley 34 is older with an age in the range 2.1 and 2.5 Gyr, E(B-V) between 0.57 and 0.64, and (m-M)0 between 14.1 and 14.3; Berkeley 36, with an age between 7.0 and 7.5 Gyr, has a reddening E(B-V)~0.50 and a distance modulus (m-M)0 between 13.1 and 13.2. For all the clusters our analysis suggests a sub-solar metallicity in accord with their position in the outer Galactic disc.