Abstract
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 EB-V = 0.099 ± 0.02, EJ-H = 0.018 ± 0.001 and EJ-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 ± 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 iso-chrones). 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.
Highlights
Open star clusters are the excellent tool to trace the properties of star formation, the formation and the evolution of the disc of our galaxies and structural points of view
Studying the old open star cluster trace back the first moments of the disc lifetime and putting crucial constraints on its formation mechanism and early evolution of the open cluster system, all this allow us to explore the history of star and cluster formation over wide range of the galaxy
Old open star cluster is very important objects, Berkeley 39 is important to re-investigate its position and age, which are estimated in a precision way from their Color-Magnitude Diagrams using the most recent Near–Infrared photometric data from the 2-Micron All Sky Survey (2MASS)
Summary
Open star clusters are the excellent tool to trace the properties of star formation, the formation and the evolution of the disc of our galaxies and structural points of view. (2015) Optical and Infrared Photometric Study of Old Open Star Cluster Berkeley 39. Old open star cluster is very important objects, Berkeley 39 is important to re-investigate its position and age, which are estimated in a precision way from their Color-Magnitude Diagrams using the most recent Near–Infrared photometric data from the 2-Micron All Sky Survey (2MASS). Other motivation of this project is to study the useful parameters to improve our knowledge about the distance scale and the kinematic properties and structures of the Milky Way Galaxy.
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