Photometric, kinematic, and variability study in the Galactic open clusters
Date & Time :
Open clusters are excellent laboratories for studies of stellar evolution as they host coeval stars born in the same physical conditions. This property of open clusters is used as constrain on the stellar evolution models. The parameters like kinetic motions, age, distance, and chemical composition are important in studies of formation and evolution of stars as well as their hosting open cluster. It is found that stars in the open clusters show various types of variability at different stages of their evolution. The study of these variable stars in the star clusters offer to understand stellar evolution scenario at various stages. The objective of the thesis is to explore the star formation and evolution through photometric, kinematic, and variability studies of the stars in the Galactic open clusters. We carried out photometric and kinematic study of 10 open clusters using UBVRcIc data, near-IR data from 2MASS, Gaia DR2 data to accomplish our objectives. The average distance to the clusters were determined using Gaia DR2 parallaxes. The log(Age) of these clusters are determined by fitting isochrone on the colour-magnitude diagrams of the clusters. The colour-magnitude diagram of NGC 2360 and SAI 45 hosts extended main-sequence turn-off which is found to be mainly caused by different rotation rates of stars. We found two step mass function slope for the open clusters NGC 381 and SAI 45. We calculated relaxation time values and found early mass segregation in IC 1442 caused by rapid dynamical evolution occurring even in very young clusters. We also carried out long-term observation for variability analysis in NGC 1960, NGC 559, and NGC 381. We found a total of 76, 70, and 57 variable stars after light curve inspection of the stars in the region of clusters NGC 1960, NGC 559, and NGC 381, respectively. We characterized the periodic variable on the basis of period, amplitude, shape, and location on the H-R diagram. The variability analysis in the thesis will enable us to understand intrinsic properties like different mode of pulsation mechanism and spurious activities as well as extrinsic properties like distribution of cool spots and binary-systems.