The radial distribution of Blue stragglers in Galactic Globular Cluster
  NGC 6656 $-$ Clues on the dynamical status
  We present dynamical status of the Galactic globular cluster NGC 6656 using
spatial distribution of Blue Straggler Stars (BSSs). A combination of
multi-wavelength high-resolution space and ground-based data are used to cover
a large cluster region. We determine the centre of gravity ($C_{grav}$) and
construct the projected density profile of the cluster using the probable
cluster members selected from HST and Gaia DR2 proper motion data sets. The
projected density profile in the investigated region is nicely reproduced by a
single mass King model, with core ($r_{c}$) and tidal ($r_{t}$) radius as
$75^{\prime\prime}.2$ $\pm$ $3^{\prime\prime}.1$ and $35^{\prime}.6$ $\pm$
$1^{\prime}.1$ respectively. In total, 90 BSSs are identified on the basis of
proper motion data in the region of radius $625^{\prime\prime}$. An average
mass of the BSSs is determined as $1.06$ $\pm$ $0.09$ $M_{\odot}$ and with an
age range of 0.5 to 7 Gyrs. The BSS radial distribution shows a bimodal trend,
with a peak in the centre, a minimum at $r \sim r_c$ and a rising tendency in
the outer region. The BSS radial distribution shows a flat behaviour in the
outermost region of the cluster. We also estimate $A^{+}_{rh}$ parameter as an
alternative indicator of the dynamical status of the cluster and is found to be
$0.038$ $\pm$ $0.016$. Based on the radial distribution and $A^{+}_{rh}$
parameter, we conclude that NGC 6656 is an intermediate dynamical age cluster.
