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arXiv · 1507.05610

Survey of Period Variations of Superhumps in SU UMa-Type Dwarf Novae. VII: The Seventh Year (2014-2015)

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

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%.

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Taichi Kato, Franz-Josef Hambsch, Pavol A. Dubovsky, Igor Kudzej, Berto Monard, Ian Miller, Hiroshi Itoh, Seiichiro Kiyota, Kazunari Masumoto, Daiki Fukushima, Hiroki Kinoshita, Kazuki Maeda, Jyunya Mikami, Risa Matsuda, Naoto Kojiguchi, Miho Kawabata, Megumi Takenaka, Katsura Matsumoto, Enrique de Miguel, Yutaka Maeda, Tomohito Ohshima, Keisuke Isogai, Roger D. Pickard, Arne Henden, Stella Kafka, Hidehiko Akazawa, Noritoshi Otani, Sakiko Ishibashi, Minako Ogi, Kenji Tanabe, Kazuyoshi Imamura, William Stein, Kiyoshi Kasai, Tonny Vanmunster, Peter Starr, Elena P. Pavlenko, Oksana I. Antonyuk, Kirill A. Antonyuk, Aleksei A. Sosnovskij, Nikolaj V. Pit, Julia V. Babina, Aleksandr Sklyanov, Rudolf Novak, Arto Oksanen, Shawn Dvorak, Raul Michel, Gianluca Masi, Colin Littlefield, Joseph Ulowetz, Sergey Yu. Shugarov, Polina Yu. Golysheva, Drahomir Chochol, Viktoriia Krushevska, Javier Ruiz, Tamas Tordai, Etienne Morelle, Richard Sabo, Hiroyuki Maehara, Michael Richmond, Natalia Katysheva, Kenji Hirosawa, William N. Goff, Franky Dubois, Ludwig Logie, Steve Rau, Irina B. Voloshina, Maksim V. Andreev, Kazuhiko Shiokawa, Vitaly V. Neustroev, George Sjoberg, Sergey Zharikov, Nick James, Greg Bolt, Tim Crawford, Denis Buczynski, Lewis M. Cook, Christopher S. Kochanek, Benjamin Shappee, Krzysztof Z. Stanek, Jose L. Prieto, Denis Denisenko, Hideo Nishimura, Masaru Mukai, Shizuo Kaneko, Seiji Ueda, Rod Stubbings, Masayuki Moriyama, Patrick Schmeer, Eddy Muyllaert, Jeremy Shears, Robert J. Modic, Kevin B. Paxson. 2015-07-20. Survey of Period Variations of Superhumps in SU UMa-Type Dwarf Novae. VII: The Seventh Year (2014-2015). https://doi.org/10.1093/pasj%2Fpsv072

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