On echo outbursts and ER UMa supercycles in SU UMa-type cataclysmic variables

I present a variation on Osaki's tidal thermal instability model for SU UMa behavior. I suggest that in systems with the lowest mass ratios, the angul ar momentum dissipation in an eccentric disk is unable to sustain the disk on the hot side of the thermal instability. This decoupling of the tidal an d thermal instabilities in systems with q less than or equal to 0.07 allows a better explanation of the "echo" outbursts of EG Cnc and the short super cycles of RZ LMi and DI UMa. The idea might also apply to the soft X-ray tr ansients.