The blue straggler population of the old open cluster Berkeley 17
  Blue Straggler Stars (BSSs) are observed in Galactic globular clusters and
old open clusters. The radial distribution of BSSs has been used to diagnose
the dynamical evolution of globular clusters. For the first time, with a
reliable sample of BSSs identified with Gaia DR2, we conduct such an analysis
for an open cluster. We identify members, including BSSs, of the oldest known
Galactic open cluster Berkeley 17 with the Gaia DR2 proper motions and
parallaxes. We study the radial distribution of the BSS population to
understand the dynamical evolution of the cluster. We select cluster members to
populate the colour magnitude diagram in the Gaia filters. Cluster parameters
are derived using the brightest members. The BSSs and giant branch stars are
identified, and their radial distributions are compared. The segregation of
BSSs is also evaluated with respect to the giant branch stars using the Minimum
Spanning Tree analysis. We determine Berkeley 17 to be at
$3138.6^{+285.5}_{-352.9}$ pc. We find 23 BSS cluster members, only two of
which were previously identified. We find a bimodal radial distribution of BSSs
supported by findings from the MST method. The bimodal radial distribution of
BSSs in Berkeley 17 indicates that they have just started to sink towards the
cluster center, placing Berkeley 17 with globular clusters of intermediate
dynamical age. This is the first such determination for an open cluster.
