Ultra-Violet Imaging Telescope Observations of the Star-Forming Ring in
  NGC7252: Evidence of Possible AGN Feedback Suppressing Central Star Formation
  Some post-merger galaxies are known to undergo a starburst phase that quickly
depletes the gas reservoir and turns it into a red-sequence galaxy, though the
details are still unclear. Here we explore the pattern of recent star formation
in the central region of the post-merger galaxy NGC7252 using high resolution
UV images from the UVIT on ASTROSAT. The UVIT images with 1.2 and 1.4 arcsec
resolution in the FUV and NUV are used to construct a FUV-NUV colour map of the
central region. The FUV-NUV pixel colour map for this canonical post-merger
galaxy reveals a blue circumnuclear ring of diameter $\sim$ 10 " (3.2 kpc) with
bluer patches located over the ring. Based on a comparison to single stellar
population models, we show that the ring is comprised of stellar populations
with ages $\lesssim$ 300 Myr, with embedded star-forming clumps of younger age
($\lesssim$ 150Myr). The suppressed star formation in the central region, along
with the recent finding of a large amount of ionised gas, leads us to speculate
that this ring may be connected to past feedback from a central super-massive
black hole that has ionised the hydrogen gas in the central $\sim$ 4" $\sim$
1.3 kpc.
