Investigation of Galactic open cluster remnants: the case of NGC 7193
  Galactic open clusters (OCs) that survive the early gas-expulsion phase are
gradually destroyed over time by the action of disruptive dynamical processes.
Their final evolutionary stages are characterized by a poorly populated
concentration of stars called open cluster remnant (OCR). This study is devoted
to assess the real physical nature of the OCR candidate NGC 7193. GMOS/Gemini
spectroscopy of 53 stars in the inner target region were obtained to derive
radial velocities and atmospheric parameters. We also employed photometric and
proper motion data. The analysis method consists of the following steps: (i)
analysis of the statistical resemblance between the cluster and a set of field
samples with respect to the sequences defined in colour-magnitude diagrams
(CMDs); (ii) a 5-dimensional iteractive exclusion routine was employed to
identify outliers from kinematical and positional data; (iii) isochrone fitting
to the $K_{s}\times(J-K_{s})$ CMD of the remaining stars and the dispersion of
spectral types along empirical sequences in the $(J-H)\times(H-K_{s})$ diagram
was checked. A group of stars was identified for which the mean heliocentric
distance is compatible with that obtained via isochrone fitting and whose
metallicities are compatible with each other. Fifteen member stars observed
spectroscopically were identified together with other 19 probable members. Our
results indicate that NGC 7193 is a genuine OCR, of an once very populous OC,
for which the following parameters were derived: $d=501\,\pm\,46\,$pc,
$t=2.5\,\pm\,1.2\,$Gyr, $\langle\,[Fe/H]\,\rangle=-0.17\,\pm\,0.23$ and
$E(B-V)=0.05\,\pm\,0.05$. Its luminosity and mass functions show depletion of
low mass stars, confirming the OCR dynamically evolved state.
