Stellar contents of two intermediate age clusters: NGC 1912 and NGC 1907

Abstract

We present CCD photometry in a wide field around two open clusters, NGC 1912 and NGC 1907. The stellar surface density profiles indicate that the radii of the clusters NGC 1912 and NGC 1907 are ~14́ and ~6́respectively. The core of the cluster NGC 1907 is found to be 1'.6 ±0'.3, whereas the core of the cluster NGC 1912 could not be defined due to its significant variation with the limiting magnitude. The clusters are situated at distances of 1400 ±100 pc (NGC 1912) and 1760 ±100 pc (NGC 1907), indicating that in spite of their close locations on the sky they may be formed in different parts of the Galaxy. Although the mass functions for the clusters are quite noisy, in the given mass range the slopes of the mass functions for clusters NGC 1912 and NGC 1907 turn out to be –1.12 ±0:30 and –1.23 ±0.21, respectively, which are in agreement with the Salpeter value. Because the ages of the clusters are much higher than the estimated relaxation time-scales, dynamical relaxation may be one of the reasons for the observed mass segregation in the clusters. A comparison of the observed CMDs of the clusters with the synthetic CMDs gives a photometric binary content as 30 ±10% (mass range 1.0 ≤ M☉ ≤ 3.1) and 20 ±10% (mass range 1.2 ≤ M☉ ≤ 3.2) in the case of NGC 1912 and NGC 1907, respectively.