The eccentric binary model of superhumps

The proposal of Papaloizou & Pringle that the superhumps in SU UMa dwarf nova systems are generated by the periodic modulation of an extended period of dynamical mass transfer flow in an eccentric binary is examined. Disc evolution models show that sufficient variation of the stream impact flux internal to the bright spot can be achieved with modest binary eccentricity. Temperatures in the disc superhump region produced by this mechanism are most likely ≈3×104K. The viscous luminosity contribution of the disc has too slow a response time to contribute to the superhumps. Stream impact and disc penetration by the stream must therefore be the main source of superhump light in this model. This may be difficult to reconcile with the need for a relatively uniform brightness distribution from eclipse data.