Determination of the degree of star concentration in globular clusters based on space observation data

Abstract

We have proposed a generalized King’s model for the observed density of stars in globular clusters (GC). Using two methods of minimizing the functional, composed in the form of the square of the difference between the theoretical and observed density values, we obtained the behavior of the degree of concentration for 26 GC. We have taken the observational data for these clusters from the work of Miocchi et al. (2013), which is a combination of ground-based and space-based observations. The minimized functional depends on three free parameters and one of them clearly characterizes the concentration of stars towards the center of the cluster. The two research methods used here give almost the same results with reasonably good accuracy. In contrast to the work of Nuritdinov et al. (2021), the χ2 method is used to determine the degree of concentration. In addition, we analyzed data from de Boer et al. (2019). However, these data do not contain information for the central regions of the clusters. The lack of these data does not allow finding the degree of concentration with the required accuracy.

Keywords

• classification problems
• globular star clusters
• concentration of stars toward the center
• observed densities of stars in clusters