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arXiv · 1604.06344

ASASSN-15jd: WZ Sge-type star with intermediate superoutburst between single and double ones

Mariko Kimura·Keisuke Isogai·Taichi Kato·Akira Imada·Naoto Kojiguchi·Yuki Sugiura·Daiki Fukushima·Nao Takeda·Katsura Matsumoto·Shawn Dvorak·Tonny Vanmunster·Pavol A. Dubovsky·Igor Kudzej·Ian Miller·Elena P. Pavlenko·Julia V. Babina·Oksana I. Antonyuk·Aleksei V. Baklanov·William L. Stein·Maksim V. Andreev·Tamás Tordai·Hiroshi Itoh·Roger D. Pickard·Daisaku Nogami
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Abstract

We present optical photometry of a WZ Sge-type dwarf nova (DN), ASASSN-15jd. Its light curve showed a small dip in the middle of the superoutburst in 2015 for the first time among WZ Sge-type DNe. The unusual light curve implies a delay in the growth of the 3:1 resonance tidal instability. Also, the light curve is similar to those of other two WZ Sge-type stars, SSS J122221.7$-$311523 and OT J184228.1$+$483742, which are believed to be the best candidates for a period bouncer on the basis of their small values of the mass ratio ($q \equiv M_{2}/M_{1}$). Additionally, the small mean superhump amplitude ($<$ 0.1 mag) and the long duration of no ordinary superhumps at the early stage of the superoutburst are common to the best candidates for a period bouncer. The average superhump period was $P_{\rm sh}$ = 0.0649810(78) d and no early superhumps were detected. Although we could not estimate the mass ratio of ASASSN-15jd with high accuracy, this object is expected to be a candidate for a period bouncer, a binary accounting for the missing population of post-period minimum cataclysmic variables, based on the above characteristics.

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Mariko Kimura, Keisuke Isogai, Taichi Kato, Akira Imada, Naoto Kojiguchi, Yuki Sugiura, Daiki Fukushima, Nao Takeda, Katsura Matsumoto, Shawn Dvorak, Tonny Vanmunster, Pavol A. Dubovsky, Igor Kudzej, Ian Miller, Elena P. Pavlenko, Julia V. Babina, Oksana I. Antonyuk, Aleksei V. Baklanov, William L. Stein, Maksim V. Andreev, Tamás Tordai, Hiroshi Itoh, Roger D. Pickard, Daisaku Nogami. 2016-04-21. ASASSN-15jd: WZ Sge-type star with intermediate superoutburst between single and double ones. https://doi.org/10.1093/pasj%2Fpsw054

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