Abstract

White dwarfs often accrete material from their remnant planetary systems, polluting their pristine hydrogen or helium atmospheres with metals. I will talk about how we can use this phenomenon to study exoplanetary compositions: photospheric metal lines can reveal the bulk compositions of the building blocks of rocky planets, while infrared emission gives us our only glimpse of the circumstellar debris before it arrives at the stellar surface. Results from dozens of systems tell us that accretion of chondritic material is common, though not universal, while the debris disks feeding accretion are dynamically active environments. The advent of JWST is opening new windows onto those disks, while large spectroscopic surveys are delivering an order-of-magnitude increase in the number of systems to study, and I will present ongoing work on both fronts.