Observing multiple populations in globular clusters with the ESO
  archive: NGC 6388 reloaded
  The metal-rich and old bulge globular cluster (GC) NGC 6388 is one of the
most massive Galactic GCs (M ~ 10^6 Msun). However, the spectroscopic
properties of its multiple stellar populations rested only on 32 red giants
(only seven of which observed with UVES, the remaining with GIRAFFE), given the
difficulties in observing a rather distant cluster, heavily contaminated by
bulge and disc field stars. We bypassed the problem using the largest telescope
facility ever: the European Southern Observatory (ESO) archive. By selecting
member stars identified by other programmes, we derive atmospheric parameters
and the full set of abundances for 15 species from high resolution UVES spectra
of another 17 red giant branch stars in NGC 6388. We confirm that no
metallicity dispersion is appreciable in this GC. About 30% of stars show the
primordial composition of first generation stars, about 20% present an
extremely modified second generation composition, and half of the stars has an
intermediate composition. The stars clearly distribute in the Al-O and Na-O
planes into three discrete groups. We find substantial hints that more than a
single class of polluters is required to reproduce the composition of the
intermediate component in NGC 6388. In the heavily polluted component the sum
Mg+Al increases as Al increases. The sum Mg+Al+Si is constant, and is the
fossil record of hot H-burning at temperatures higher than about 70 MK in the
first generation polluters that contributed to form multiple populations in
this cluster.
