A wide view of different stellar sub-populations and evolutionary phases in globular clusters

Combining wide-field ground-based photometry to HST data for the core of Galactic globular clusters (GGCs), is a powerful tool to investigate the spatial distribution of multiple stellar populations and stars in different evolutionary phases throughout their extension.We analyzed Omega Cen and NGC2808 by using DECam and HST photometry, and employed color-color planes and proper motions to select clean samples of cluster stars. Color indices were used to select sub-populations with different chemical enrichment: our analysis reveals that most enriched stars are more centrally concentrated compared to the primordial ones in both GGCs, while showing a more extended spatial distribution in the outskirts. We also found a decreasing fraction of the hottest horizontal branch stars with increasing distance from the core. To validate the results and better understand the GGC formation scenario, spectroscopy of stars in the outskirts with 4MOST-VISTA or MOONS-VLT is crucial to measure their abundances and radial velocities. We will extend our analysis to other massive GGCs, such as NGC1851, 47 Tuc, NGC362, NGC288, M2, and M15, using available DECam, Megacam and VST wide-field photometry and HST data.These studies are important test-benches for the larger projects we can undertake with Vera Rubin Observatory and the Nancy Roman telescope; these facilities will enable detailed studies of other Local Group globular clusters, allowing comparison of their properties with GGCs.