AN IMPLEMENTATION OF BAYESIAN FRAMEWORK IN DETERMINING PROJECTED SPATIAL DISTRIBUTIONS OF STAR CLUSTERS

• Main Author: Arif Hidayat, Yuda
• Format: Theses
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/39211
• Institution: Institut Teknologi Bandung

Star clusters are groups of stars that are bonded to each other by their gravitational forces. In general, star clusters are divided into the globular cluster and open cluster. There will always be some dynamic interactions in their lifetime, i.e. the process of relaxation and equipartition of interstellar encounter energy. The aims of this study are (1) to construct the models of various spatial distributions of globular cluster and open cluster with the age of < 107 and > 107 using Bayesian evidence; (2) to calculate the posterior ratio of the model or Bayes factor using the Bayesian framework and determine the best model of spatial distribution of globular cluster and open cluster; (3) to determine the total mass and estimate the mass segregation of the globular cluster and open cluster. The modelling is done by using King, GKing (Generalised King), OGKing (Optimised Generalised King), EFF (Elson Fll Freeman), GDP (Generalised Density Prole), and RGDP (Restricted Generalised Density Prole) proles. Based on the Bayes factor, the results of a review of the density structure for star clusters aged > 107 year (Melotte 22, Blanco 1, and NGC 6397) are dominated by King group proles (King, GKing, and OGKing) while for < 107 year, IC 1396 is dominated by EFF prole on symmetrical model. Ellipticity values at the core radius (rc) and tidal radius (rt) obtained for Melotte 22, Blanco 1, IC 1396, and NGC 6397 are 0:07+0:44 ????0:01 and 0:38+0:25 ????0:18, 0:07+0:56 ????0:01 and 0:10+0:66 ????0:01, 0:28+0:32 ????0:13 and 0:44+0:38 ????0:22, 0:01+0:01 ????0:01 and 6:10????3 10????3,respectively. The estimation of the occurrence of mass segregation can be viewed from the value of . The value obtained for each star clusters are 0:14+0:05 ????0:02; 0:06+0:10 ????0:24; 0:11+0:15 ????0:08; and 10:35+0:09 ????0:12 which means that each star clusters has mass segregation. The total mass obtained for each group using the tidal force relationship of gravitational interactions with the potential of Galaxy are 3805, 1259, 3174, and 10.23x105(M) respectively.