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The presence of planetary material in white dwarf atmospheres, thought to beaccreted from a dusty debris disc produced via the tidal disruption of aplanetesimal, is common. Approximately five per cent of these discs host aco-orbital gaseous component detectable via emission from atomic transitions -usually the 8600 Angstrom CaII triplet. These emission profiles can be highlyvariable in both morphology and strength. Furthermore, the morphologicalvariations in a few systems have been shown to be periodic, likely produced byan apsidally precessing asymmetric disc. Of the known gaseous debris discs,that around HE1349-2305 has the most rapidly evolving emission line morphology,and we present updated spectroscopy of the CaII triplet of this system. Theadditional observations show that the emission line morphologies varyperiodically and consistently, and we constrain the period to two aliases of459$\pm$3d and 502$\pm$3d. We produce images of the CaII triplet emission fromthe disc in velocity space using Doppler tomography - only the second suchimaging of a white dwarf debris disc. We suggest that the asymmetric nature ofthese velocity images is generated by gas moving on eccentric orbits withradially-dependent excitation conditions via photo-ionisation from the whitedwarf. We also obtained short-cadence (~ 4 min) spectroscopy to search forvariability on the time-scale of the disc's orbital period (~ hours) due to thepresence of a planetesimal, and rule out variability at a level of ~ 1.4 percent.

Velocity-imaging the rapidly precessing planetary disc around the white dwarf HE 1349-2305 using Doppler tomography