White dwarfs and planets on small and large scales

Astronomers are able to use "dead" white dwarf stars and destroyed planets to learn about planets and asteroids orbiting stars other than our Sun. Planets and asteroids can be scattered close to the white dwarf and tidally disrupted.

Then the composition of the parent body can be determined by spectroscopic observation of the material accreted into the white dwarf atmosphere.

This is the only means we have to directly probe the bulk composition of extra-Solar planets and asteroids, complementing studies of atmospheric composition.This project addresses key issues surrounding this process: - Study of the accretion of tidally disrupted fragments onto the white dwarf, telling us how reliable our present interpretations of the observations are. - Study of how asteroids observed in transit orbiting some white dwarfs influence the evolution of discs made from these fragments, such as by resonant trapping and interruption to the accretion process. - Study of the Galactic orbits of white dwarfs and how planetary systems differ around white dwarfs of different ages, whose progentitors had different compositions.This project will link the small scale of what happens to destroyed planetary material close to a white dwarf, to the large scale of the white dwarf´s age and properties within the Galaxy.

This will tell us how different kinds of planets have formed throughout the Galaxy´s history, and our own Earth´s place in this history.