Survey of Period Variations of Superhumps in SU UMa-Type Dwarf Novae. IV: The Fourth Year (2011-2012)
Creators: name: Kato, Taichi
name: Hambsch, Franz-Josef
name: Maehara, Hiroyuki
name: Masi, Gianluca
name: Miller, Ian
name: Noguchi, Ryo
name: Akasaka, Chihiro
name: Aoki, Tomoya
name: Kobayashi, Hiroshi
name: Matsumoto, Katsura
name: Nakagawa, Shinichi
name: Nakazato, Takuma
name: Nomoto, Takashi
name: Ogura, Kazuyuki
name: Ono, Rikako
name: Taniuchi, Keisuke
name: Stein, William
name: Henden, Arne
name: de Miguel, Enrique
name: Kiyota, Seiichiro
name: Dubovsky, Pavol A.
name: Kudzej, Igor
name: Imamura, Kazuyoshi
name: Akazawa, Hidehiko
name: Takagi, Ryosuke
name: Wakabayashi, Yuya
name: Ogi, Minako
name: Tanabe, Kenji
name: Ulowetz, Joseph
name: Morelle, Etienne
name: Pickard, Roger D.
name: Ohshima, Tomohito
name: Kasai, Kiyoshi
name: Pavlenko, Elena P.
name: Antonyuk, Oksana I.
name: Baklanov, Aleksei V.
name: Antonyuk, Kirill
name: Samsonov, Denis
name: Pit, Nikolaj
name: Sosnovskij, Aleksei
name: Littlefield, Colin
name: Sabo, Richard
name: Ruiz, Javier
name: Krajci, Thomas
name: Dvorak, Shawn
name: Oksanen, Arto
name: Hirosawa, Kenji
name: Goff, William N.
name: Monard, Berto
name: Shears, Jeremy
name: Boyd, David
name: Voloshina, Irina B.
name: Shugarov, Sergey Yu.
name: Chochol, Drahomir
name: Miyashita, Atsushi
name: Pietz, Jochen
name: Katysheva, Natalia
name: Itoh, Hiroshi
name: Bolt, Greg
name: Andreev, Maksim V.
name: Parakhin, Nikolai
name: Malanushenko, Viktor
name: Martinelli, Fabio
name: Denisenko, Denis
name: Stockdale, Chris
name: Starr, Peter
name: Simonsen, Mike
name: Tristram, Paul. J.
name: Fukui, Akihiko
name: Tordai, Tamas
name: Fidrich, Robert
name: Paxson, Kevin B.
name: Itagaki, Koh-ichi
name: Nakashima, Youichirou
name: Yoshida, Seiichi
name: Nishimura, Hideo
name: Kryachko, Timur V.
name: Samokhvalov, Andrey V.
name: Korotkiy, Stanislav A.
name: Satovski, Boris L.
name: Stubbings, Rod
name: Poyner, Gary
name: Muyllaert, Eddy
name: Gerke, Vladimir
name: MacDonald, Walter
name: Linnolt, Michael
name: Maeda, Yutaka
name: Hautecler, Hubert
Publisher: name: arXiv
Year: 2012
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 studied 86 SU UMa-type dwarf novae. We confirmed the general trends such as the relation between period derivatives and orbital periods. There are some systems showing positive period derivatives despite the long orbital periods. We observed the 2011 outburst of the WZ Sge-type dwarf nova BW Scl, and recorded an O-C diagram similar to those of previously known WZ Sge-type dwarf novae. The WZ Sge-type dwarf nova OT J184228.1+483742 showed an unusual pattern of double outbursts composed of an outburst with early superhumps and one with ordinary superhumps. We propose an interpretation that a very small growth rate of the 3:1 resonance due to an extremely low mass-ratio led to a quenching of the superoutburst before the ordinary superhumps appeared. We studied ER UMa-type dwarf novae and found that V1159 Ori showed positive superhumps similar to ER UMa in the 1990s. The recently recognized ER UMa-type object BK Lyn dominantly showed negative superhumps, and its behavior was very similar to the present-day state of ER UMa. The pattern of period variations in AM CVn-type objects were very similar to short-period hydrogen-rich SU UMa-type dwarf novae, making them helium analogue of hydrogen-rich SU UMa-type dwarf novae. SBS 1108+574, a peculiar hydrogen-rich dwarf nova below the period minimum, showed a very similar pattern of period variations to those of short-period SU UMa-type dwarf novae. The mass-ratio derived from the detected orbital period suggests that this secondary is a somewhat evolved star whose hydrogen envelope was mostly stripped during the mass-exchange. CC Scl, MASTER OT J072948.66+593824.4 and OT J173516.9+154708 showed only low-amplitude superhumps with complex profiles. These superhumps are likely a combination of closely separated two periods.
description: 81 pages, 92 figures, PASJ in press, correction in the author list and text