Superhumps and repetitive rebrightenings of the WZ Sge-type dwarf nova, EG Cancri

We report on time-resolved photometric observations of the WZ Sge-type dwarf nova, EG Cnc (Huruhata's variable), during its superoutburst in 1996-1997. EG Cnc, after the main superoutburst accompanied by the development of superhumps typical of a WZ Sue-type dwarf nova, exhibited a series of six major rebrightenings. During these rebrightenings and the following long fading tail, EG Cue persistently showed superhumps having a period equal to the superhump period observed during the main superoutburst. The persistent superhumps had a constant superhump flux with respect to the rebrightening phase. These findings suggest that the superhumps observed during the rebrightening stage and the fading tail are a remnant of the usual superhumps, and are not newly triggered by rebrightenings. By a comparison with the 1977 Outburst of this object and outbursts of other WZ Sae-type dwarf novae, we propose an activity sequence of WZ Sge-type superoutbursts, in which the current outburst of EG Cue is placed between a single-rebrightening event and distinct outbursts separated by a dip. The post-superoutburst behavior of WZ Sge-type dwarf novae can be understood in the presence of a considerable amount of remnant matter behind the cooling front in the outer accretion disk, even after the main superoutburst. We consider that a premature quenching of the hot state due to the weak tidal effect under the extreme mass ratio of the WZ S-e-type binary is responsible for the origin of the remnant mass.