Hogg 12 and NGC 3590: A New Open Cluster Binary System Candidate

PIATTI, A. E.; CLARIÁ, J. J.; 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 photometry down to V~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, our evidence is sufficient to confirm 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±0.05, located at a heliocentric distance d=2.0±0.5 kpc, and of an age similar to that of NGC 3590 (t=30 Myr). Both clusters are surprisingly small objects whose radii are barely ~1 pc, andthey 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. Of the ~180 open cluster binary systems estimated to exist in the Galaxy, of which 27 are actually well known, Hogg 12 and NGC 3590 appear to be one of the two closest pairs.