16247

A complete characterization of the spatial distributions of the different multiple stellar populations in Omega Centauri is of fundamental importance to study their formation and dynamical history. Recent studies have revealed a very complex picture of this cluster and found the presence of 15 different sub-populations groups. While previous studies have found a radial gradient in the number fraction of the two major groups of stellar populations comma nothing is known about the radial variation of all the other groups of sub-populations. Studies of all the sub-populations are available in the core (from the literature) and in the outermost regions (from HST archival observations) of the cluster comma while data in the intermediate regions are missing. These intermediate regions are those where the strongest radial gradient of the two major groups of stars has been found and they are thus essential to explore possible structural differences between all the different sub-groups. Here we propose to collect the missing observations needed to separate and identify all the sub-groups multiple populations in these intermediate regions. This will give us the opportunity to obtain the necessary radial coverage to trace for the first time the radial gradient of all the multiple populations along almost the entire cluster. Such a major improvement requires a relatively modest investment of only two additional HST orbits.