CSS121123:045020-093113: A WZ Sge-type dwarf nova amongst the AM CVn systems
ATel #4726; P. A. Woudt (U. Cape Town), B. Warner (U. Cape Town), M. Motsoaledi (U. Cape Town)
on 11 Jan 2013; 12:11 UT
Credential Certification: Patrick Woudt (pwoudt@ast.uct.ac.za)
Subjects: Cataclysmic Variable
Further to ATel#4678, we report the detection of a photometric modulation of 47.28 ± 0.01 min in the helium dwarf nova CSS121123:045020-093113 with a possible 2-day alias at 46.50 ± 0.01 min. At this long period for AM CVn dwarf novae, CSS121123:045020-093113 is located uniquely amongst known AM CVn systems that are thought to be permanently in a quiescent state.
Observations were made with the Sutherland High-speed Optical Camera (SHOC) on 08.79-09.00 and 10.82-10.90 Jan 2013 UT when the system was at V ~ 19.1, during its return to quiescence (V ~ 20.5) after its November 2012 outburst of V ~ 14.8.
We propose that this object is the equivalent amongst the AM CVn population of the hydrogen-rich WZ Sge dwarf novae, and that the November 2012 outburst was a superoutburst. This is supported by the fact that only a single, large amplitude outburst has been recorded for CSS121123:045020-093113 over a 9-year time span in the CRTS data base, and that it resides at an orbital period range associated with very low-mass transfer rates in AM CVn systems.
