Study of UV bright sources in globular cluster NGC 4590 using
  Ultraviolet Imaging Telescope (UVIT) observations
  We have studied ultraviolet (UV) bright sources in the Galactic globular
cluster (GGC) NGC 4590 using Ultraviolet Imaging Telescope (UVIT) on-board the
\mbox{{\em AstroSat}} satellite. Using UV-optical color-magnitude diagrams
(CMDs), we have identified and characterized the sources of different
evolutionary stages i.e., blue horizontal branch stars (BHBs), extremely blue
horizontal branch stars (EHBs), blue straggler stars (BSs), variable stars,
etc. We estimated effective temperature (T$_{\mathrm{eff}}$), gravity
($\log$(g)), luminosity (L$_{bol}$), and hence the radius (R) of these hot
stars by fitting spectral energy distribution (SED) with the help of stellar
atmosphere models. Two new far-UV (FUV) bright cluster member stars situated
near the core of the cluster have been detected; one of them is an EHB star and
the other one is either in its post-blue hook evolutionary phase or in white
dwarf phase. The evolutionary status of all the hot stars, identified in the
cluster, has been investigated by using various evolutionary models. We find
the massive and younger BSs are concentrated at the center of the cluster
whereas the older and less massive BSs are distributed though out the cluster.
The BSs normalized radial distribution seems to be bi-modal with a minimum
located at r$_{\mathrm{min}}$ = 4.3 r$_c$. We calculated A$^+$ parameter of the
cluster which is obtained using cumulative normalized radial distribution of
horizontal branch stars (HBs) and BSs. We measured this value up to half-mass
radius of the cluster to be $+ 0.13$, which indicates that NGC 4590 is one of
the youngest clusters among dynamically intermediate age GGCs with a dynamical
age of $0.423\pm0.096$ Gyr.
