DECam photometry reveals extra-tidal stars around the Milky Way globular
  cluster NGC 6864 (M75)
  Globular clusters are prone to lose stars while moving around the Milky Way.
These stars escape the clusters and are distributed throughout extended
envelopes or tidal tails. However, such extra-tidal structures are not observed
in all globular clusters, and yet there is no structural or dynamical
parameters that can predict their presence or absence. NGC\,6864 is an outer
halo globular cluster with reported no observed tidal tails. We used Dark
Energy Camera (DECam) photometry reaching $\sim$ 4 mag underneath its main
sequence turnoff to confidently detect an extra-tidal envelope, and stellar
debris spread across the cluster outskirts. These features emerged once robust
field star filtering techniques were applied to the fainter end of the observed
cluster main sequence. NGC\,6864 is associated to the {\it Gaia}-Enceladus
dwarf galaxy, among others 28 globular clusters. Up-to-date, nearly 64$\%$ of
them have been targeted looking for tidal tails and most of them have been
confirmed to exhibit tidal tails. Thus, the present outcomes allow us to
speculate on the possibility that {\it Gaia}-Enceladus globular clusters share
a common pattern of mass loss by tidal disruption.
