Photometric studies of open star clusters Haffner 11 and Czernik 31

Abstract

We present the broad band UBVI CCD photometric investigations in the region of the two open clusters Haffner 11 and Czernik 31. The radii of the clusters are determined as 3'.5 and 3'.0 for Haffner 11 and Czernik 31 respectively. Using two colour (U-B) versus (B-V) diagram we determine the reddening E(B-V) 1⁄4 0:50 Æ 0.05 mag and 0.48 ± 0.05 mag for the cluster Haffner 11 and Czernik 31 respectively. Using 2MASS JHK s and optical data, we determined E(J-K)= 0.27 ± 0.06 mag and E(V-K) = 1.37 ± 0.06 for Haffner 11 and E(J-K)= 0.26 ± 0.08 mag and E(V-K) = 1.32 ± 0.08 mag for Czernik 31. Our analysis indicate normal interstellar extinction law in the direction of both the clus- ters. Distance of the clusters is determined as 5.8 ± 0.5 Kpc for Haffner 11 and 3.2 ± 0.3 Kpc for Czernik 31 by comparing the ZAMS with the CM diagram of the clusters. The age of the cluster has been estimated as 800 ± 100 Myr for Haffner 11 and 160 ± 40 Myr for Czernik 31 using the stellar isochrones of metallicity Z =0.019