Stars, galaxies and cosmology in the nearby Universe
The basic tenets of the prevailing cosmological paradigm - Lambda-Cold Dark Matter (ΛCDM) - are generally well understood and robust to large scale observables, such as the cosmic microwave background and galaxy clustering. The past few years has seen the focus of cosmological studies shift into a new “precision” regime. Modern simulations of galaxy formation are very successful at using our current, incomplete, understanding of baryonic evolutionary processes to provide testable predictions about the small scale distribution of mass and light in and around galaxies. The onus, therefore, is to obtain data which will provide critical tests of the models on galactic scales and hence advance these important cosmological theories. It is here that observations of the closest galaxies - in particular our own Milky Way, the Andromeda Galaxy, and their companions within the Local Group of galaxies - provide some of the strongest constraints and biggest challenges for the cosmological model. I will discuss recent observational results concerning the properties of mass and light around our closest galactic neighbours, showing how observations of individual stars lend clues towards galaxy evolution that inform the development of our cosmological models. I will also discuss what I consider likely future developments for this field, with an eye towards the next generation of astronomical facilities.