Ruprecht 147: a paradigm of dissolving star cluster
  We employed recent Gaia/DR2 data to investigate the dynamical status of the
nearby (300 pc), old (2.5 Gyr) open cluster Ruprecht~147. We found prominent
leading and trailing tails of stars along the cluster orbit, which demonstrates
that Ruprecht~147 is losing stars at fast pace. Star counts indicate the
cluster has a core radius of 33.3 arcmin, and a tidal radius of 137.5 arcmin.
The cluster also possesses an extended corona, which cannot be reproduced by a
simple King model. We computed the present-day cluster mass using its
luminosity and mass function, and derived an estimate of 234$\pm$52
$M_{\odot}$. We also estimated the cluster original mass using available
recipes extracted from N-body simulations obtaining a mass at birth of
50000$\pm$6500 $M_{\odot}$. Therefore dynamical mass loss, mostly caused by
tidal interaction with the Milky Way, reduced the cluster mass by about 99\%.
We then conclude that Ruprecht~147 is rapidly dissolving into the general
Galactic disc.
