Globular Clusters of the Milky Way

Image: Distribution of metallicity in the Milky Way (solid blue bars), and M31 (red outlines) globular cluster populations.

Globular clusters are found around many types of galaxies and are some of the oldest and brightest objects we can detect. Their tight gravitationally bound stars allow them to better withstand the forces of galactic mergers and interactions. This allows us to probe the formation and evolutionary history of the galaxies they inhabit.

Focusing specifically on their metallicity and colour, I applied a Gaussian mixture modelling code tease out sub-populations within the GCs of the Milky Way.

I arrived at the same bimodal distribution found in other works dividing the Milky Way globular cluster population into a metal-rich and metal-poor population at [Fe/H] = -0.8dex, and -1.0dex for M31.