| Abstract : |
Globular clusters (GCs) are ideal astrophysical laboratories to test our understanding of stellar evolution, especially at the low-mass end. Galactic GCs harbour many stars which are bright in the ultraviolet wavebands. These hot stars exist in various canonical and non-canonical stellar evolutionary phases such as blue and extreme horizontal branch (EHB), post-horizontal branch (pHB), blue straggler, and white dwarfs. Most of these are late stages of evolution which progress relatively fast and hence the number of these types of stars observed per cluster is statistically low. The knowledge regarding their formation scenarios and evolutionary pathways is also limited. Hot stars belonging to the EHB and pHB stages are speculated to be causing the ‘UV-upturn’ seen in the spectra of elliptical galaxies making their study highly relevant. In this talk, I will discuss how we used the excellent capabilities of AstroSat/UVIT combining it with other datasets from HST, Gaia, and ground-based telescopes to carry out the first census of hot and luminous UV-bright pHB members of the massive and dense GC NGC 2808. I will present an extensive discussion on their physical properties and evolutionary status. I will also talk about the expected and observed number statistics of such objects in the cluster. Finally, I will also present the preliminary results from the first FUV observations of the most massive galactic GC, Omega Centauri. |
