Talk Title: Variability in Planetary Debris Discs Around White Dwarfs
A significant fraction of white dwarfs host remnant planetary systems, signposted by dusty debris discs fed by the tidal disruption of a rocky planetesimal. Some also contain gas, indicating that these are dynamically active systems. Repeated observations of these gas discs show variations on both long (decadal) and short (hourly) time-scales. I will present the first image of a gaseous debris disc, produced from fourteen years of spectroscopic monitoring of the prototypical SDSS J1228+1040, discuss possible explanations of the short-term variability, and the overall understanding of these gaseous discs in the context of evolved planetary systems.