  Of the 21 known gaseous debris discs around white dwarfs, a large fraction of
them display observational features that are well described by an eccentric
distribution of gas. In the absence of embedded objects or additional forces,
these discs should not remain eccentric for long timescales, and should instead
circularise due to viscous spreading. The metal pollution and infrared excess
we observe from these stars is consistent with the presence of tidally
disrupted sub-stellar bodies. We demonstrate, using smoothed particle
hydrodynamics, that a sublimating or partially disrupting planet on an
eccentric orbit around a white dwarf will form and maintain a gas disc with an
eccentricity within 0.1 of, and lower than, that of the orbiting body. We also
demonstrate that the eccentric gas disc observed around the white dwarf SDSS
J1228+1040 can be explained by the same hypothesis.
