  Terzan 5 is a stellar system located in the Galactic Bulge, at a distance of
5.9 kpc. Recent discoveries show that it hosts two stellar populations with
different iron abundance ({\Delta}[Fe/H]=0.5). Such a large difference has been
measured only in {\omega} Centauri in the Galactic halo. Moreover no
anticorrelation is observed in Terzan 5, hence it is not a genuine globular
cluster. The observed chemical patterns are strikingly similar to those
observed in the Bulge stars. This suggests that Terzan 5 is a remnant fragment
of the Galactic bulge.

Astrophysics of Galaxies