Problems of Determining the Degree of Star Concentration Towards the Center of Globular Clusters

In this paper, we analyze the apparent surface density observations of 81 globular clusters provided by Gaia DR2. The problems of analyzing these observations and their differences from similar data obtained using the HST are discussed. Based on the results of this analysis of the quality of observational data and a number of physical considerations, we separate globular clusters into three classes and then consider the issues of modeling the apparent surface density versus distance. The values of the free parameters of the model are found by the symplectic minimization method. The free parameters including the concentration parameter are for the first time found using the 4-parameter generalized model we propose.