* Astronomy

Title: OT J002656.6+284933 (CSS101212:002657+284933): SU UMa-Type Dwarf Nova with Longest Superhump Period
Author: Taichi Kato (Kyoto U), Tamas Tordai, Colin Littlefield, Kiyoshi Kasai, Sergey Yu. Shugarov, Natalia Katysheva, Anna M. Zaostrojnykh, Roger D. Pickard, Enrique de Miguel, Kirill Antonyuk, Oksana Antonyuk, Elena P. Pavlenko, Nikolai Pit, Hiroshi Itoh, Javier Ruiz, Keisuke Isogai, Mariko Kimura, Yasuyuki Wakamatsu, Tonny Vanmunster, Geoff Stone

We observed the 2016 outburst of OT J002656.6+284933 (CSS101212:002657+284933) and found that it has the longest recorded [0.13225(1) d in average] superhumps among SU UMa-type dwarf novae. The object is the third known SU UMa-type dwarf nova above the period gap. The outburst, however, was unlike ordinary long-period SU UMa-type dwarf novae in that it showed two post-outburst rebrightenings. It showed superhump evolution similar to short-period SU UMa-type dwarf novae. We could constrain the mass ratio to less than 0.15 (most likely between 0.10 and 0.15) by using superhump periods in the early and post-superoutburst stages. These results suggest the possibility that OT J002656.6+284933 has an anomalously undermassive secondary and it should have passed a different evolutionary track from the standard one.

Read more (970kb, PDF)