A study of extreme extra-solar planetary systems

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Examining white dwarfs with metal-polluted atmospheres is a route to measuring the bulk composition of exo-planetesimals, providing important input into our understanding of planet formation. Data from the Gaia space mission will be the key to increase the number of known white dwarfs by an order of magnitude, with the first major data release planned for April 2018, allowing large-sample statistics to be derived. This project is focussed on identifying and analysing polluted white dwarfs to investigate the chemical composition of rocky bodies in extrasolar systems. We will use ultraviolet spectroscopy for 69 white dwarfs, recorded as part of a HST Snapshot program, before expanding the project to include Gaia DR2 targets. Ground-based spectroscopy collected using the next-generation instruments WEAVE and DESI will also be analysed. We will subsequently examine trends in abundances as a function of white dwarf mass (and hence mass of the progenitor planet host) and cooling/system age - current works may have been limited by small numbers of available targets - to investigate the effects of galactic evolution on the formation of exo-planetary systems.