Investigating multiple populations in Globular clusters.

Spectroscopic studies have demonstrated that nearly all Galactic globular clusters harbour multiple stellar populations with different chemical compositions. Moreover, colour-magnitude diagrams based exclusively on photometry allow us to easily identify and characterise multiple populations in a large number of clusters. It is currently debated if multiple populations are present along all evolutionary phases, or whether stars belonging to populations with most anomalous chemical composition avoid certain evolutionary phases, among which is the Asymptotic Giant Branch. SkyMapper u and v band photometry is expected to be particularly powerful to trace multiple populations in globular cluster. Answering the question whether multiple populations are present across all stellar evolutionary phases has important implications for understanding the formation of globular clusters, and validate or not stellar evolutionary theories. 

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Caption to figure: Left panel: colour magnitude diagram of stars in the red giant (yellow) and asymptotic giant branch phase (blue) of the Globular Cluster M3. Right panels: the colour spread of stars belonging to these evolutionary phases (yellow and blue histograms) is larger than observational uncertainties (gray histogram), indicating the presence of multiple populations in both evolutionary phases.