The 2006 November Outburst of EG Aquarii: the SU UMa Nature Revealed

• Published in: Publications of the Astronomical Society of Japan Vol. 60; no. 5; pp. 1151 - 1158
• Main Authors: Imada, Akira, Stubbings, Rod, Kato, Taichi, Uemura, Makoto, Krajci, Thomas, Torii, Ken’ichi, Sugiyasu, Kei, Kubota, Kaori, Moritani, Yuuki, Ishioka, Ryoko, Masi, Gianluca, Kiyota, Seiichiro, Monard, L. A. G., Maehara, Hiroyuki, Nakajima, Kazuhiro, Arai, Akira, Ohsugi, Takashi, Yamashita, Takuya, Kawabata, Koji S., Nagae, Osamu, Chiyonobu, Shingo, Fukazawa, Yasushi, Mizuno, Tsunefumi, Katagiri, Hideaki, Takahashi, Hiromitsu, Ueda, Atsushi, Hayashi, Takehiro, Okita, Kiichi, Yoshida, Michitoshi, Yanagisawa, Kenshi, Sato, Shuji, Kino, Masaru, Kitagawa, Masahiro, Sadakane, Kozo, Nogami, Daisaku
• Format: Journal Article
• Language: English
• Published: Oxford, UK Oxford University Press 25-10-2008
• Subjects: stars: dwarf novae; stars: oscillations; accretion, accretion disks; stars: individual (EG Aquarii); novae, cataclysmic variables
• ISSN: 0004-6264; 2053-051X
• DOI: 10.1093/pasj/60.5.1151

We report on time-resolved CCD photometry of the cataclysmic variable EG Aquarii during a 2006 November outburst. During the outburst, superhumps were unambiguously detected with a mean period of 0.078828(6) d, allowing for the first time to classify the object as an SU UMa-type dwarf nova. It also turned out that the outburst contained a precursor. At the end of the precursor, immature profiles of humps were observed. By a phase analysis of these humps, we interpreted the features as being superhumps. This is the second example that the superhumps were shown during a precursor. Near the maximum stage of the outburst, we discovered an abrupt shift of the superhump period by
${\sim\;}$
0.002 d. After the supermaximum, the superhump period decreased at a rate of
$\dot{P}/P =$
$-$
8.2
${\;\times\;}$
10
$^{-5}$
, which is typical for SU UMa-type dwarf novae. Although the outburst light curve was characteristic of SU UMa-type dwarf novae, long-term monitoring of the variable shows no outbursts over the past decade. We also comment on the basic properties of long period and inactive SU UMa-type dwarf novae.