Hogg\,12 and NGC\,3590: a new open cluster binary system candidate

PIATTI, ANDRÉS E.; CLARIA OLMEDO, JUAN JOSÉ; AHUMADA, A.V.

PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF THE PACIFIC

UNIV CHICAGO PRESS

Año: 2010 vol. 122 p. 516 - 523

0004-6280

We have obtained CCD $UBVI_{KC}$ photometry down to V $\sim$ 22.0 for the open clusters  Hogg\,12 and NGC\,3590 and the fields surrounding them. Based on photometric and morphological criteria, as well as on the stellar density in the region, we present enough evidence to affirm that Hogg\,12 is a genuine open cluster. NGC\,3590 was used as a control cluster. The color-magnitude diagrams of Hogg\,12, cleaned from field star contamination, reveal that this is a solar metal content cluster, affected by $E(B-V)$ = 0.40 $\pm$ 0.05, located at a heliocentric distance $d$ = 2.0 $\pm$ 0.5 kpc and of an age similar to that of NGC\,3590({\it t} = 30 Myr). Both clusters are surprinsingly small objects  whose radii are barely $\sim$ 1 pc  and which are separated in the sky by scarcely 3.6 pc. These facts, added to their similar ages, reddenings and metallicities, allow us to consider them a new open cluster binary system candidate. Out of the $\sim$ 180 open cluster binary systems estimated to exist in the Galaxy, out of which 27 are actually well known, Hogg\,12 and NGC\,3590 appear to be one of the two closest pairs.