Our observations show star behaviour that so far have never been detected during a rebrightening phase among WZ Sge-type dwarf novae with multiple rebrightenings.
We report observations and analysis of the 2019 superoutburst of the star 'TCP J21040470+4631129'. This object showed a 9-mag superoutburst with early superhumps and ordinary superhumps, which are the features of WZ Sge-type dwarf novae.
The spectra during the postsuperoutburst stage showed the Balmer, He I and possible sodium doublet features. The mass ratio is derived as 0.0880(9) from the period of the superhump.
To induce a superoutburst during the brightening phase, the accretion disk was needed to expand beyond the 3:1 resonance radius of the system again after the main superoutburst.
These peculiar phenomena can be explained by the enhanced viscosity and large radius of the disk suggested by the higher luminosity and the presence of late-stage superhumps during the post-superoutburst stage, plus by more mass supply from the cool mass reservoir and/or from the secondary because of the enhanced mass transfer than those of other WZ Sge-type dwarf novae.
Link to the scientific publicatiom: https://arxiv.org/pdf/2004.10508