| Abstract : | We present the multi-wavelength study of hot stellar population in Galactic Globular clusters (GGCs). We targeted four GGCs in this work i.e., NGC 4590, NGC 6218, NGC 6838, and NGC 7078. To select the genuine cluster members, we used HST and Gaia EDR3 astro-photometric catalogs. This allows us to select the BSS and reference population from the center to the outskirts of the GCs. We have obtained the dynamical status of these GCs using high-resolution and multi-wavelength data by using radial distribution of BSS with respect to the reference population and determine the Arh parameter. Based on the BSS radial distribution and Arh parameter, we found that NGC 4590 is a dynamically young age cluster with Family I classification, NGC 6218 is in intermediate dynamical age cluster of Family II classification, and NGC 6838 & NGC 7078 are in dynamical old age cluster of Family III classification. We also estimated tau (HB) parameter for these four clusters to parametrize the extent of HB morphology and to relate with the possible ``second parameters''. We choose clusters with different pair of matallicities, i,e., high, intermediate and low. The tau (HB) parameter follow a quadratic anti-correlation with [Fe/H], indicating that metallicity indeed is the ``first parameter''. We found a linear correlation between age and and an anti-correlation with ``mass loss'' parameter w.r.t tau (HB) parameter, which suggest that age and mass-loss along RGB could be the possible ``second parameters''. |
