Hogg 12 and NGC 3590: A new open cluster binary system candidate

Abstract

We have obtained CCD UBVI(KC) photometry down to V = 22 for the open clusters Hogg 12 and NGC 3590 and their surrounding fields. We confirm the physical reality of Hogg 12 like a genuine open cluster from photometric, morphologican and space density criteria; NGC 3590 served as a control cluster. The extracted-cleaned photometry of Hogg 12 reveals that the cluster is of solar metal content, affected by a E(B-V) color excess of 0.40 mag, and placed at a distance from the Sun of d = 2.0 kpc, if a Sun´s distance from the center of the Galaxy of 8.5 kpc is assumed. Hogg 12 appears to be as old as NGC 3590 (t = 30 Myr). Both clusters are surprisingly small objects with radii of approximately 1 pc and scarsely separated by 3.6 pc, which, besides to their similar ages, reddenings and metallicities, becomes them in a new candidate open cluster binary system. Out of approximately 180 open cluster binary systems estimated to exist in the Galaxy, they are one of the two closest pairs between 27 actaully known.