On the physical size of the Milky Way globular cluster NGC 7089 (M 2)
  We study the outer regions of the Milky Way globular cluster NGC 7089 based
on new Dark Energy Camera (DECam) observations. The resulting background
cleaned stellar density profile reveals the existence of an extended envelope.
We confirm previous results that cluster stars are found out to ~ 1deg from the
cluster's centre, which is nearly three times the value of the most robust
tidal radii estimations. We also used results from direct N-body simulations in
order to compare with the observations. We found a fairly good agreement
between the observed and numerically generated stellar density profiles.
Because of the existence of gaps and substructures along globular cluster tidal
tails, we closely examined the structure of the outer cluster region beyond the
Jacobi radius. We extended the analysis to a sample of 35 globular clusters, 20
of them with observed tidal tails. We found that if the stellar density profile
follows a power law ~ r**(-alpha), the alpha slope correlates with the globular
cluster present mass, in the sense that, the more massive the globular cluster
the smaller the alpha value. This trend is not found in globular clusters
without observed tidal tails. The origin of such a phenomenon could be related,
among other reasons, to the proposed so-called potential escapers or to the
formation of globular clusters within dark matter mini-haloes.
