UVIT study of UV bright stars in the globular cluster NGC 4147
  We present far ultraviolet (FUV) observations of globular cluster NGC 4147
using three FUV filters, BaF2 (F154W), Sapphire (F169M), and Silica (F172M) of
Ultra-Violet Imaging Telescope (UVIT) on-board the \mbox{{\em AstroSat}}
satellite. We confirmed the cluster membership of the UVIT observed sources
using proper motions from Gaia data release 2 (GAIA DR2). We identified 37 blue
horizontal branch stars (BHBs), one blue straggler star (BSS) and 15 variable
stars using UV-optical color magnitude diagrams (CMDs). We find that all the
FUV bright BHBs are second generation population stars. Using UV-optical CMDs,
we identify two sub-populations, BHB1 and BHB2, among the UV-bright BHBs in the
cluster with stars count ratio of 24:13 for BHB1 and BHB2. The effective
temperatures (T$_{\mathrm{eff}}$) of BHB1 and BHB2 were derived using
color-temperature relation of BaSTI-IAC zero-age horizontal branch (ZAHB). We
found that BHB1 stars are more centrally concentrated than BHB2 stars. We also
derive physical parameters of the detected FUV bright BSS by fitting younger
age BaSTI-IAC isochrones on optical and UV-optical CMDs.
