Optical and Infrared Photometric Study of Old Open Star Cluster Berkeley 39
International Journal of Astronomy and Astrophysics International Journal of Astronomy and Astrophysics
In this paper we present astrophysical parameters of the very old open star cluster Berkeley 39 using 2MASS JHK data and observation of BV CCD photometry (V ~ 21.5 mag) in Johnson-Cousin filters. We have derived reddening, distance, metallicity and age etc. using two color diagrams in near-infrared and optical bands. We have found E B-V = 0.099 ± 0.02, E J-H = 0.018 ± 0.001 and E J-Ks = 0.016 ± 0.001 mag, and the distance modulus of (m-M) 0 = 13.24 ± 0.03 mag, which give a distance of 4.2 ±
... stance of 4.2 ± 0.04 Kpc, and the age of the cluster is 5.6 Gyr with metallicity; Z = 0.008 (obtained from fitting of the observed CMDs with Padova isochrones). The radius of the cluster obtained from the analysis of 2MASS data is equal 9.0 ± 0.13 arc minutes; it reflects that the cluster have large radius with new cluster center. Luminosity and mass functions have been investigated as well as the dynamical relaxation time of the cluster Berkeley 39.