The precessing gas rings around WD1145+017
Abstract: Approximately 30% of white dwarfs are polluted by metals, the result of accretion onto the stellar surface by rocky bodies that have been tidally disrupted. These systems thus offer a direct window onto the interior composition of rocky planetesimals. Disks of these metals are also observed in emission around a subset of polluted white dwarfs from which the radial extent of the orbiting gas has been determined. The (so far) geometrically-unique polluted white dwarf WD1145+017 provides a different perspective on the gaseous debris: it is seen in absorption against the stellar disk, in addition to optical light transits of opaque dust clouds. I will discuss our ongoing monitoring and interpretation of the circumstellar line profiles observed towards WD1145+017. The velocity information contained in the absorption line profiles allows constraints to be placed on the geometric configuration of the gaseous material and, due to the relatively short variability timescale, offers an exciting opportunity to test general relativistic theories of disk precession around white dwarfs.