Survey of Period Variations of Superhumps in SU UMa-Type Dwarf Novae. VII: The Seventh Year (2014-2015)
Creators: name: Kato, Taichi
name: Hambsch, Franz-Josef
name: Dubovsky, Pavol A.
name: Kudzej, Igor
name: Monard, Berto
name: Miller, Ian
name: Itoh, Hiroshi
name: Kiyota, Seiichiro
name: Masumoto, Kazunari
name: Fukushima, Daiki
name: Kinoshita, Hiroki
name: Maeda, Kazuki
name: Mikami, Jyunya
name: Matsuda, Risa
name: Kojiguchi, Naoto
name: Kawabata, Miho
name: Takenaka, Megumi
name: Matsumoto, Katsura
name: de Miguel, Enrique
name: Maeda, Yutaka
name: Ohshima, Tomohito
name: Isogai, Keisuke
name: Pickard, Roger D.
name: Henden, Arne
name: Kafka, Stella
name: Akazawa, Hidehiko
name: Otani, Noritoshi
name: Ishibashi, Sakiko
name: Ogi, Minako
name: Tanabe, Kenji
name: Imamura, Kazuyoshi
name: Stein, William
name: Kasai, Kiyoshi
name: Vanmunster, Tonny
name: Starr, Peter
name: Pavlenko, Elena P.
name: Antonyuk, Oksana I.
name: Antonyuk, Kirill A.
name: Sosnovskij, Aleksei A.
name: Pit, Nikolaj V.
name: Babina, Julia V.
name: Sklyanov, Aleksandr
name: Novak, Rudolf
name: Oksanen, Arto
name: Dvorak, Shawn
name: Michel, Raul
name: Masi, Gianluca
name: Littlefield, Colin
name: Ulowetz, Joseph
name: Shugarov, Sergey Yu.
name: Golysheva, Polina Yu.
name: Chochol, Drahomir
name: Krushevska, Viktoriia
name: Ruiz, Javier
name: Tordai, Tamas
name: Morelle, Etienne
name: Sabo, Richard
name: Maehara, Hiroyuki
name: Richmond, Michael
name: Katysheva, Natalia
name: Hirosawa, Kenji
name: Goff, William N.
name: Dubois, Franky
name: Logie, Ludwig
name: Rau, Steve
name: Voloshina, Irina B.
name: Andreev, Maksim V.
name: Shiokawa, Kazuhiko
name: Neustroev, Vitaly V.
name: Sjoberg, George
name: Zharikov, Sergey
name: James, Nick
name: Bolt, Greg
name: Crawford, Tim
name: Buczynski, Denis
name: Cook, Lewis M.
name: Kochanek, Christopher S.
name: Shappee, Benjamin
name: Stanek, Krzysztof Z.
name: Prieto, Jose L.
name: Denisenko, Denis
name: Nishimura, Hideo
name: Mukai, Masaru
name: Kaneko, Shizuo
name: Ueda, Seiji
name: Stubbings, Rod
name: Moriyama, Masayuki
name: Schmeer, Patrick
name: Muyllaert, Eddy
name: Shears, Jeremy
name: Modic, Robert J.
name: Paxson, Kevin B.
Publisher: name: arXiv
Year: 2015
Subjects: subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: FOS: Physical sciences
subject: FOS: Physical sciences

description: Continuing the project described by Kato et al. (2009, arXiv:0905.1757), we collected times of superhump maxima for 102 SU UMa-type dwarf novae observed mainly during the 2014-2015 season and characterized these objects. Our project has greatly improved the statistics of the distribution of orbital periods, which is a good approximation of the distribution of cataclysmic variables at the terminal evolutionary stage, and confirmed the presence of a period minimum at a period of 0.053 d and a period spike just above this period. The number density monotonically decreased toward the longer period and there was no strong indication of a period gap. We detected possible negative superhumps in Z Cha. It is possible that normal outbursts are also suppressed by the presence of a disk tilt in this system. There was no indication of enhanced orbital humps just preceding the superoutburst, and this result favors the thermal-tidal disk instability as the origin of superoutbursts. We detected superhumps in three AM CVn-type dwarf novae. Our observations and recent other detections suggest that 8% of objects showing dwarf nova-type outbursts are AM CVn-type objects. AM CVn-type objects and EI Psc-type object may be more abundant than previously recognized. OT J213806, a WZ Sge-type object, exhibited a remarkably different feature between the 2010 and 2014 superoutbursts. Although the 2014 superoutburst was much fainter the plateau phase was shorter than the 2010 one, the course of the rebrightening phase was similar. This object indicates that the O-C diagrams of superhumps can be indeed variable at least in WZ Sge-type objects. Four deeply eclipsing SU UMa-type dwarf novae (ASASSN-13cx, ASASSN-14ag, ASASSN-15bu, NSV 4618) were identified. We studied long-term trends in supercycles in MM Hya and CY UMa and found systematic variations of supercycles of ~20%.
description: 116 pages, 151 figures, accepted for publication in PASJ