Abstract

Exoplanets are ubiquitous across the Milky Way, but only a handful of planets have been discovered around white dwarf stars. Although so few in tact planets have been found, there is extensive evidence for the survival of planetary material to the white dwarf phase. At least 30% of white dwarfs are observed with signatures of swallowed exoplanets in their atmospheres, and a fraction of these show evidence for circumstellar debris. From these ‘polluted’ white dwarfs, we can uniquely infer the bulk composition of the exoplanetary parent body that was accreted. This talk will provide an observational overview of these enigmatic systems, from the outer circumstellar regions to the white dwarf atmospheres. How does this exoplanetary material ultimately end up in the atmosphere of these white dwarfs? What is the composition of the planetary material that has polluted the white dwarfs? What can this composition tell us about exoplanetary material and geological processes in exoplanetary systems?