Spectroscopic analysis of VVV CL001 cluster with MUSE
  Like most spiral galaxies, the Milky Way contains a population of blue,
metal-poor globular clusters and another of red, metal-rich ones. Most of the
latter belong to the bulge, and therefore they are poorly studied compared to
the blue (halo) ones because they suffer higher extinction and larger
contamination from field stars. These intrinsic difficulties, together with a
lack of low-mass bulge globular clusters, are reasons to believe that their
census is not complete yet. Indeed, a few new clusters have been confirmed in
the last few years. One of them is VVV CL001, the subject of the present study.
We present a new spectroscopic analysis of the recently confirmed globular
cluster VVV CL001, made by means of MUSE@VLT integral field data. Individual
spectra were extracted for stars in the VVV CL001 field. Radial velocities were
derived by cross-correlation with synthetic templates. Coupled with PMs from
the VVV survey, these data allow us to select 55 potential cluster members, for
which we derive metallicities using the public code The Cannon. The mean radial
velocity of the cluster is Vhelio = -324.9 +- 0.8 km/s,as estimated from 55
cluster members. This high velocity, together with a low metallicity [Fe/H] =
-2.04 +- 0.02 dex suggests that VVV CL001 could be a very old cluster. The
estimated distance is d = 8.23 +- 0.46 kpc, placing the cluster in the Galactic
bulge. Furthermore, both its current position and the orbital parameters
suggest that VVV CL001 is most probably a bulge globular cluster.
