The Recently Discovered Dwarf Nova System ASAS J002511+1217.2: A New WZ Sagittae Star

The cataclysmic variable ASAS J002511+1217.2 was discovered in outburst by the All-Sky Automated Survey (ASAS) in 2004 September, and intensively monitored by AAVSO observers through the following 2 months. Both photometry and spectroscopy indicate that this is a very short period system. Clearly defined superhumps with a period of 0.05687 ± 0.00001 (1 σ) days (81.9 minutes) are present during the superoutburst, 5 to 18 days following the ASAS detection. We observe a change in superhump profile similar to the transition to "late superhumps" observed in other short-period systems; the superhump period appears to increase slightly for a time before returning to the original value, with the resulting superhump phase offset by approximately half a period. We detect variations with a period of 0.05666 ± 0.00003 (1 σ) days (81.6 minutes) during the 4 day quiescent phase between the end of the main outburst and the single echo outburst. Weak variations having the original superhump period reappear during the echo and its rapid decline. Time-resolved spectroscopy conducted nearly 30 days after detection and well into the decline yields an orbital period measurement of 82 ± 5 minutes. Both narrow and broad components are present in the emission-line spectra, indicating the presence of multiple emission regions. The weight of the observational evidence suggests that ASAS J002511+1217.2 is a WZ Sge-type dwarf nova, and we discuss how this system fits into the WZ classification scheme.