We report photometric and spectroscopic observations and analysis of the 2019 superoutburst of 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. Five rebrightenings were observed after the main superoutburst. The spectra during the post-superoutburst 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. During the third and fifth rebrightenings, growing superhumps and superoutbursts were observed, which have never been detected during a rebrightening phase among WZ Sge-type dwarf novae with multiple rebrightenings. 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.

中文翻译：

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在 WZ Sge 型矮新星重新亮化阶段首次探测到两次超级爆发：TCP J21040470+4631129

我们报告了 2019 年 TCP J21040470+4631129 超爆发的光度学和光谱学观察和分析。该天体显示了一次 9 等级的超爆发，具有早期超驼峰和普通超驼峰，这是 WZ Sge 型矮新星的特征。在主超爆发后观察到了五次再增亮。超爆发后阶段的光谱显示了巴尔默、He I 和可能的钠双峰特征。质量比是从超驼峰时期推导出来的 0.0880(9)。在第三次和第五次重亮期间，观察到了不断增长的超驼峰和超级爆发，这在多次重亮的 WZ Sge 型矮新星中从未在重亮阶段被发现。为了在增亮阶段引发超级爆发，吸积盘需要扩展到 3 之外：主超爆发后系统再次共振半径为1。这些奇特的现象可以通过较高的光度和超爆发后阶段后期超驼峰的存在所暗示的盘的粘性增强和大半径来解释，加上来自冷物质库和/或来自冷物质库的更多物质供应。次生是因为比其他 WZ Sge 型矮新星的传质增强。