ASTRODEBATA / Nicola Gentile Fusillo: White dwarfs, dust, disks and debris: a unique look at the composition of exo-rocks

White dwarfs, dust, disks and debris: a unique look at the composition of exo-rocks

Nicola Gentile Fusillo
Università degli studi di Trieste, Italija

The vast majority of all stars in the galaxy, including our Sun and virtually all known planet hosts share the same ultimate fate: one day they will become white dwarfs, small stellar embers destined to cool and fade over billions of years. Today we know that planets can survive the final evolution of their host stars and a number of white dwarfs show evidence of the presence of remnants of planetary systems in the form of metal pollution of their otherwise pristine H or He atmosphere. This pollution results from the accretion of circumstellar debris created by tidal disruption of rocky planetesimals scattered too close to the white dwarf. Modelling the spectra of these metal-polluted white dwarfs allows one to measure the relative abundances of the polluting elements and so reconstruct the bulk chemical composition of the accreted body. In addition to being the only venue to probe the composition of rocky material outside our solar system, these ancient systems also allow us to study the evolution of planetary systems. The seminar will provide a brief overview of the state of the art of this new research area highlighting some key discoveries as well as the current challenges and the progress to be made in the near future.

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