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WZ Sge-type dwarf novae with multiple rebrightenings: MASTER OT J211258.65+242145.4 and MASTER OT J203749.39+552210.3

From the abstract: We have made a survey of WZ Sge-type dwarf novae with multiple rebrightenings, and confirmed that the superhump periods of WZ Sge-type dwarf novae with multiple rebrightenings were longer than those of WZ Sge-type dwarf novae without a rebrightening. Although WZ Sge-type dwarf novae with multiple rebrightenings have been thought to be the good candidates for period bouncers based on their low mass ratio (q) from inferred from the period of fully grown (stage B) superhumps, our new method using the period of growing superhumps (stage A superhumps), however, implies higher q than those expected from stage B superhumps. These q values appear to be consistent with the duration of the stage A superoutbursts, which likely reflects the growth time of the 3:1 resonance. We present a working hypothesis that the small fractional superhump excesses for stage B superhumps in these systems may be explained as a result that a higher gas pressure effect works in these systems than in ordinary SU UMa-type dwarf novae. This result leads to a new picture that WZ Sge-type dwarf novae with multiple rebrightenings and SU UMa-type dwarf novae without a rebrightening (they are not period bouncers) are located in the same place on the evolutionary track.

Authors: Chikako Nakata, Tomohito Ohshima, Taichi Kato, Daisaku Nogami, Gianluca Masi, Enrique de Miguel, Joseph Ulowetz, Colin Littlefield, William N. Goff, Thomas Krajci, Hiroyuki Maehara, William Stein, Richard Sabo, Ryo Noguchi, Rikako Ono, Miho Kawabata, Hisami Furukawa, Katsura Matsumoto, Takehiro Ishibashi, Pavol A. Dubovsky, Igor Kudzej, Shawn Dvorak, Franz-Josef Hambsch, Roger D. Pickard, Etienne Morelle, Eddy Muyllaert, Stefano Padovan, Arne Henden

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