ASASSN-18aan: 晩期G型の伴星を伴った軌道周期3.6時間の食を起こすSU Uma型激変星

京都大学新制・課程博士博士(理学)甲第23014号理博第4691号新制||理||1673(附属図書館)京都大学大学院理学研究科物理学・宇宙物理学専攻(主査)准教授 野上 大作, 教授 嶺重 慎, 教授 太田 耕司学位規則第4条第1項該当Doctor of ScienceKyoto UniversityDFA

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OT J002656.6+284933 (CSS101212:002657+284933): An SU UMa-Type Dwarf Nova with Longest Superhump Period

We observed the 2016 outburst of OT J002656.6+284933 (CSS101212:002657+284933) and found that it has the longest recorded [0.13225(1) d in average] superhumps among SU UMa-type dwarf novae. The object is the third known SU UMa-type dwarf nova above the period gap. The outburst, however, was unlike ordinary long-period SU UMa-type dwarf novae in that it showed two post-outburst rebrightenings. It showed superhump evolution similar to short-period SU UMa-type dwarf novae. We could constrain the mass ratio to less than 0.15 (most likely between 0.10 and 0.15) by using superhump periods in the early and post-superoutburst stages. These results suggest the possibility that OT J002656.6+284933 has an anomalously undermassive secondary and it should have passed a different evolutionary track from the standard one.Comment: 6 pages, 3 figures, accepted for publication in PASJ (Letters), Note added in proof has been added. Supplementary Information (si.pdf) is available in the source fil