Abstract | This thesis is devoted to the study of the stellar parameters and determination of stellar distances. For that purpose, the BEAST (The Bayesian Extinction and Stellar Tool) algorithm was used. BEAST is fitting ultraviolet to near-infrared photometric magnitudes to precomputed model grids. This method precisely evaluates parameters such as age, mass, metallicity, and distance by implementing Bayesian inference combined with prior distributions best-suited to the characteristics of the stellar population under study. BEAST integrates synthetic photometry and uses chi-squared fitting techniques that handle observational data from large surveys. This study was focused on globular clusters M92, M13 and NGC 6791 and with the help of BEAST the following parameters were determined: mass, luminosity, surface gravity, radius, temperature, distance, age and metallicity of the stars we studied. We also determined dust parameters: visual extinction and ratio of total to selective extinction. We later compared values from other science papers and values obtained by the BEAST. For M92, BEAST determined the mean distance to be 5.46 kpc (accuracy of 66.6%). For age, BEAST determinated the value of 7.45 Gyr (accuracy of 67.7%). For visual extinction in magnitude, BEAST got Av = 0.12 (accuracy of 47.3%) and for ratio of total to selective extinction, Rv = 2.76 (accuracy of 89%). For M13, BEAST BEAST determinated mean distance to be 5.01 kpc (accuracy of 63.67%). For age, it determinated 7.67 Gyr (accuracy of 65.84%). For visual extinction in magnitude BEAST got Av = 0.16 (accuracy of 87.5%) and for ratio of total to selective extinction, Rv = 3.49 (accuracy of 88.83%). For NGC 6791, BEAST calculated mean distance to be equal to 4.55 kpc (accuracy of 92.98%), which is an excellent result. In that cluster we analysed SGB and RGB stars, while in other clusters we analysed AGB, RGB and HB stars, so it might be the case that BEAST is doing better estimates for stars in earlier stages of their evolution. For age, BEAST estimated the value of 7.77 Gyr (accuracy of 93.61%). For visual extinction in magnitude we obtained Av = 0.46 (accuracy of 65.71%) and for ratio of total to selective extinction, Rv = 3.01 (accuracy of 97.1%). We have also shown that fixing stellar age does not influence the determination of other stellar and dust parameters, while fixing distance can greatly influence stellar luminosity and radii. BEAST is very effective in dealing with the challenges posed by interstellar dust extinction, which can greatly affect the accuracy of photometric data. The results are not perfect, but they show the effectiveness of Bayesian methods in dealing with complex data in astronomy. |