Program: GS-2013A-Q-23

In the globular cluster (GC)-like system Terzan5 we recently discovered (Ferraro et al. 2009, Nature 462, 483) two distinct stellar populations defining two separated Red Clumps (RCs) and showing both a significantly different iron content (Delta[Fe/H]~0.5 dex) and a striking chemical similarity with the bulge stars. This evidence strongly suggests that Terzan5 is the fossil of one of the pristine units that generated the Galactic bulge. Here we propose to exploit the superior capabilities of GSAOI/GeMS to (1) accurately measure the age of the two Terzan5 populations from the main sequence turn-off luminosities, and (2) investigate the RC morphology of 5 GC-like systems in the bulge (Liller1, Terzan6, NGC6440, NGC6569 and NGC6624) with characteristics very similar to Terzan5. Precisely dating the first and second burst of star formation in Terzan5 is crucial for the correct reconstruction of its evolutionary history. Unveiling new systems with an RC split similar to that of Terzan5 is urged to verify whether other fossil relics of the bulge are orbiting the Galaxy. Indeed, the results of the proposed observations promise to have a dramatic impact on our understanding of the formation processes of the Milky Way bulge and, more in general, of galactic spheroids.