Investigation of the radial metallicity gradient in our galaxy via open clusters

In this thesis, the photometric analysis of 39 open clusters which located the opposite direction from the Galaxy center are performed and astrophysical parameters are determined. Taking into account these parameters, the radial metallicity gradient is investigated. The CCD UBV photometric observations of 15 open clusters are performed with 1m T100 telescope located in TÜBİTAK National Observatory (TUG), the photometric data of the remaining 24 clusters are taken from studies literature. Photometric and astrometric data are used in selection of cluster member stars. Taking into account the cluster member stars, the astrophysical parameters are determined. The color excesses and metallicities of the clusters are calculated via independent methods, while distance modulus and age are determined simultaneously with PARSEC isochrones which are fitted to the most probable member stars of the clusters on color-magnitude diagrams. The consistence of the cluster distances and astrometric data indicated that there are no degeneragy among the cluster astrophysical parameters calculated via independent methods. In the analysis of the radial metallicity gradient obtained between the metallicity calculated via photometric metallicity calibration using the most probable F-G type main sequence stars of the clusters and distances from the Galaxy center is determined strong in the distance range of 6 < Rgc < 9 kpc with value of d[Fe/H]/dRgc = -0.053  0.014 dex/kpc, while it is calculated weak between 9 ≤ Rgc < 12 kpc with value of d[Fe/H]/dRgc = -0.018  0.010 dex/kpc. In the calculation of radial metallicity gradient, it is shown that the scattering in the metallicities are to be due to the fact that some open clusters move in the eccentric Galactic orbits. Altough similar radial metallicity gradients are obtained in comparison between the models that contain the two-infall scenario of our Galaxy and young open clusters, a significant difference is determined between the Galactic chemical evolution model and metallicity values. The analysis of cluster member stars with different luminosities explain the differences in calculating the metallicity of the clusters.