The Young Open Cluster Ngc 2244 Of Their Own And Members Of The Research

The young open cluster NGC 2244 is investigated in this thesis. Absolute proper motions for 495 stars referred to the Tycho-2 and their probabilities of membership have been determined. We discussed some characteristics of NGC 2244 using these results. The partially embedded cluster NGC 2244, as one of the youngest open clusters with an evolutionary age of about 2Myrs, is located in the center of Rosette Nebula. It lies at a distance of 1.4kpc, and its average reddening of E(B-V) is 0.47. It provides an excellent sample for the study of star formation and their early evolution. As the main part of the thesis, we studied the absolute proper motions of NGC 2244 in detail, using photographic plates of Shanghai Observatory, which were taken with the 40cm double astrograph of focal length 6.9m at sheshan, with a time span of 35 years. Membership probabilities were assigned by a maximum likelihood analysis of the distribution of the 2-D positions and proper motions of stars with a ten–free-parameter model. Our membership determining is efficient, as shown in the probability histogram, which laid the foundation of the further study of physical properties of the cluster. We discussed some physical properties of NGC 2244 based on our membership probabilities and 2MASS data, such as the radius of the cluster, pre-main sequence stars, and apparent Ks-band luminosity function.