As part of a study aimed at determining the kinematical and chemical
properties of Terzan 5, we present the first characterization of the bulge
stars surrounding this puzzling stellar system. We observed 615 targets located
well beyond the tidal radius of Terzan 5 and we found that their radial
velocity distribution is well described by a Gaussian function peaked at
=+21.0\pm4.6 km/s and with dispersion sigma_v=113.0\pm2.7 km/s. This is
the one of the few high-precision spectroscopic survey of radial velocities for
a large sample of bulge stars in such a low and positive latitude environment
(b=+1.7{\deg}). We found no evidence for the peak at \sim+200 km/s found
in Nidever et al. 2012. The strong contamination of many observed spectra by
TiO bands prevented us from deriving the iron abundance for the entire
spectroscopic sample, introducing a selection bias. The metallicity
distribution was finally derived for a sub-sample of 112 stars in a magnitude
range where the effect of the selection bias is negligible. The distribution is
quite broad and roughly peaked at solar metallicity ([Fe/H]\simeq+0.05 dex)
with a similar number of stars in the super-solar and in the sub-solar ranges.
The population number ratios in different metallicity ranges agree well with
those observed in other low-latitude bulge fields suggesting (i) the possible
presence of a plateau for |b|<4{\deg} for the ratio between stars in the
super-solar (0<[Fe/H]<0.5 dex) and sub-solar (-0.5<[Fe/H]<0 dex) metallicity
ranges; (ii) a severe drop of the metal-poor component ([Fe/H]<-0.5) as a
function of Galactic latitude.Comment: 27 pages, 9 figures, accepted for publication by Ap
