SCYON Abstract

Received on July 11 2007

Stellar Contents of Two Intermediate Age Clusters: NGC 1912 and NGC 1907

AuthorsAnil K. Pandey (1,2), Saurabh Sharma (1), Karunakar Upadhyay (1), Katsuo Ogura (3), Tejbir S. Sandhu (1), Hirouki Mito (4), and Ram Sagar (1)
Affiliation(1) Aryabhatta Research Institute of Observational Sciences (ARIES), Nainital, 263 129, India
(2) Institute of Astronomy, National Central University, Chung-Li 32054, Taiwan
(3) Kokugakuin University, Higashi, Shibuya-ku, Tokyo 150-8440, Japan
(4) Kiso Observatory, School of Science, University of Tokyo, Mitake-mura, Kiso-gun, Nagano 397-0101, Japan
Accepted byPublication of the ASJ
Contactsaurabh2aries.ernet.in
URLhttp://aries.ernet.in
Links NGC 1912 / NGC 1907

Abstract

We present deep CCD photometry in a wide field around two open clusters NGC 1912 and NGC 1907. Stellar surface density profile indicates that the radius of the cluster NGC 1912 and NGC 1907 is ~14 arcmin and ~6 arcmin respectively. The core of the cluster NGC 1907 is found to be 1.6±0.3 arcmin, whereas the core of the cluster NGC 1912 could not be defined due to its significant variation with the limiting magnitude. The colour-colour diagrams indicate a mean uniform reddening E(B-V) = 0.25±0.05 mag and 0.50±0.05 mag across the clusters NGC 1912 and NGC 1907 respectively. The age of the clusters is found to be ~300 Myr. The clusters are situated at distance of 1400±70 pc (NGC 1912) and 1780±80 pc (NGC 1907), indicating that these clusters may be formed in different parts of the Galaxy. The mass function slope is derived by applying corrections of field star contamination and data incompleteness. The derived mass function for the cluster is quite noisy, however in the given mass range the slope of the mass function for the clusters NGC 1912 and NGC 1907 comes out to be -1.12±0.30 and -1.23±0.21 respectively which is in agreement with the Salpeter value. The age of the clusters is much higher than the estimated relaxation time-scale, therefore 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(sun) ≤ 3.1) and 20±10% (mass range 1.2 ≤ M(sun) ≤ 3.2) in the case of NGC 1912 and NGC 1907 respectively.