Multiple populations in Galactic globular clusters: a survey in the Str��mgren system

We are coming to believe that stellar populations in globular clusters are not as simple as they were once thought to be. A growing amount of photometric and spectroscopic evidence shows that globular clusters host at least two different stellar populations. In our contribution to these proceedings we present the first results of a survey we are conducting to look for the presence of multiple populations in a significant number of Galactic globular clusters, using the Str��mgren system. We intend to photometrically separate these populations and characterize their radial distributions and extensions.
4 pages, 2 figures. To appear in the proceedings of "Reading the book of globular clusters with the lens of stellar evolution", in the Memorie della Societa Astronomica Italiana