On the extended stellar structure around NGC 288
  We report on observational evidence of an extra-tidal clumpy structure around
NGC 288 from an homogeneous coverage of a large area with the Pan-STARRS PS1
database. The extra-tidal star population has been disentangled from that of
the Milky Way field by using a cleaning technique that successfully reproduced
the stellar density, luminosity function and colour distributions of MW field
stars. We have produced the cluster stellar density radial profile and a
stellar density map from independent approaches, from which we found results in
excellent agreement : the feature extends up to 3.5 times the cluster tidal
radius. Previous works based on shallower photometric data sets have speculated
on the existence of several long tidal tails, similar to that found in Pal 5.
The present outcome shows that NGC 288 could hardly have such tails, but
favours the notion that interactions with the MW tidal field has been a
relatively inefficient process for stripping stars off the cluster. These
results point to the need of a renewed overall study of the external regions of
Galactic globular clusters (GGCs) in order to reliably characterise them.
Hence, it will be possible to investigate whether there is any connection
between detected tidal tails, extra-tidal stellar populations, extent diffuse
halo-like structures with the GGCs' dynamical histories in the Galaxy.
