Most of the current observational efforts in finding the chemical
imprints left by the first stars have focused on the most metal-poor
(and probably oldest) stars found in the MW halo. Very metal-poor stars
were also found in ultra-faint dwarf galaxies, which are intriguing
dark-matter dominated objects with very low average metallicities.
Studies based on the chemical and kinematic properties of stars in the
different MW components have shown that not only the halo, but also the
bulge is a potential host of some of the oldest stars in our Galaxy. The
oldest Globular Cluster of the MW is located in the Bulge (Barbuy et al.
2009), and recently it has been possible to measure ages for microlensed
dwarf stars in the Bulge, finding very old objects. These both
observational results show that the oldest objects in the Bulge have
metallicities around [Fe/H] = -1, hence offering a new window on the
First Stars (Chiappini et al. 2011). Indeed, the correspondence between
age and metallicity is strongly dependent on the star formation history
of the particular studied component, and this suggestion has far
reaching implications.What I would like to show in my talk is the
importance Planetary Nebulae can play in this hot field. I will show
that by studying the PNe metallicity bulge distribution one can
highlight the "old Bulge" component. Once this important observational
constraint is used to guide chemical evolution models of the oldest
bulge population, one can use these models to look for imprints of the
first stars in the bulge. A comparison with what we have found so far
for the halo, and the new insights we can get by adding the Galactic
Bulge in this interesting topic will be shown and discussed.
