Signposts of Planetary Systems Around Stellar Remnants

Roman Rafikov, Cambridge University - 8.5.17


A significant fraction of the white dwarfs - end products of the low and intermediate mass stellar evolution - show presence of metals in their atmospheres, suggesting external pollution with high-Z elements. More than 30 of such metal-enriched white dwarfs have been recently found to harbor dense, compact disks of debris, both particulate and gaseous. In my talk I will show that the best explanation for the origin of these disks is their production through tidal disruption of minor planets that originate from the planetary systems of these white dwarf. These objects can thus inform us (posthumously) about planet formation around stars of intermediate (>2 MSun) mass. They also provide us with unprecedented information about the bulk composition of the extrasolar minor bodies, not accessible by any other means. I will also describe the processes governing the evolution of the circum-white dwarf debris disks and determining the rate at which high-Z planetary material ultimately accretes onto the white dwarfs, resulting in the observed metal pollution of their atmospheres.