Planets or asteroids? A geochemical method to constrain the masses of White Dwarf pollutants (video)

The PLATO mission will discover a large number of terrestrial exoplanets, providing measurements of their radii. However, to determine whether an exoplanet is ‘Earth-like’, we must also understand its geological composition. The composition of a planet has wide ranging implications for its subsequent evolution and habitability. Ground-based follow-up to the PLATO detections can constrain planet masses and inform our knowledge of planetary interiors. In this talk, I will discuss a complimentary technique that can further improve our understanding of planetary composition and the geology of rocky exoplanets.

Polluted white dwarfs which have accreted fragments of rocky objects provide a unique opportunity to probe exoplanetary interiors. These accreted fragments are often rich in either core-like or mantle-like material, which inform us about the core and mantle compositions we can expect to find in exoplanetary bodies.

In this talk, I will present an approach to modelling the abundances of non-Earth-like core and mantle compositions observed in polluted white dwarfs. We use data from metal-silicate partitioning experiments to calculate the effect of non-Earth-like conditions on the distribution of elements between the core and the mantle. The resulting non-Earth-like compositions may be useful for interior structure models of exoplanets.