The central regions of our Galaxy are dominated by the crowded stellar bulge. Although stars in the bulge are typically observed to be almost as abundant in metals as the sun, the bulge is generally considered to have been one of the earliest parts of the Galaxy to form. 

This project is on microlensed stars in the Galactic bulge. Microlensing occurs when a "lens" object (typically a low-mass star) becomes closely aligned with a more distant "source" star, whose image it magnifies and brightens. In the case of the bulge, the source stars are dwarfs which become bright enough while they are being microlensed (typically for a couple of weeks) to allow high resolution spectroscopy. So far, about 48 examples have been observed in this way, and some of them appear to be quite young. This does not fit into the usual picture of an old bulge.