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Superoutbursts in WZ Sge-type dwarf novae (DNe) are characterized by both early superhumps and ordinary superhumps originating from the 2 : 1 and 3 : 1 resonances, respectively. However, some WZ Sge-type DNe show a superoutburst lacking early superhumps; it is not well established how these differ from superoutbursts with an early superhump phase. We report time-resolved photometric observations of the WZ Sge-type DN V627 Peg during its 2021 superoutburst. The detection of ordinary superhumps before the superoutburst peak highlights that this 2021 superoutburst of V627 Peg, like that in 2014, did not feature an early superhump phase. The duration of stage B superhumps was slightly longer in the 2010 superoutburst accompanied by early superhumps than that in the 2014 and 2021 superoutbursts, which lacked early superhumps. This result suggests that an accretion disk experiencing the 2 : 1 resonance may have a larger mass at the inner part of the disk and hence needs more time for the inner disk to become eccentric. The presence of a precursor outburst in the 2021 superoutburst suggests that the maximum disk radius should be smaller than that of the 2014 superoutburst, even though the duration of quiescence was longer than that before the 2021 superoutburst. This could be accomplished if the 2021 superoutburst was triggered as an inside-out outburst or if the mass transfer rate in quiescence changes by a factor of two, suggesting that the outburst mechanism and quiescence state of WZ Sge-type DNe may have more variety than ever thought.

 

Abstract Continuing the project described by Kato et al. (2009, PASJ, 61, S395), we collected times of superhump maxima for 102 SU UMa-type dwarf novae observed mainly during the 2017 season, and characterized these objects. WZ Sge-type stars identified in this study are PT And, ASASSN-17ei, ASASSN-17el, ASASSN-17es, ASASSN-17fn, ASASSN-17fz, ASASSN-17hw, ASASSN-17kd, ASASSN-17la, PNV J20205397$+$2508145, and TCP J00332502$-$3518565. We obtained new mass ratios for seven objects using growing superhumps (stage A). ASASSN-17gf is an EI Psc-type object below the period minimum. CRTS J080941.3$+$171528 and DDE 51 are objects in the period gap, and both showed a long-lasting phase of stage A superhumps. We also summarize the recent advances in understanding of SU UMa-type and WZ Sge-type dwarf novae.