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 bythe All-Sky Automated Survey in September 2004, and intensively monitored byAAVSO observers through the following two months. Both photometry andspectroscopy indicate that this is a very short-period system. Clearly definedsuperhumps with a period of 0.05687 +/- 0.00001 days (1-sigma) are presentduring the superoutburst, 5 to 18 days following the ASAS detection. We observea change in superhump profile similar to the transition to ``late superhumps''observed in other short-period systems; the superhump period appears toincrease slightly for a time before returning to the original value, with theresulting superhump phase offset by approximately half a period. We detectvariations with a period of 0.05666 +/- 0.00003 days (1-sigma) during thefour-day quiescent phase between the end of the main outburst and the singleecho outburst. Weak variations having the original superhump period reappearduring the echo and its rapid decline. Time-resolved spectroscopy conductednearly 30 days after detection and well into the decline yields an orbitalperiod measurement of 82 +/- 5 minutes. Both narrow and broad components arepresent in the emission line spectra, indicating the presence of multipleemission regions. The weight of the observational evidence suggests that ASASJ002511+1217.2 is a WZ Sge-type dwarf nova, and we discuss how this system fitsinto the WZ classification scheme.Comment: 24 pages, 11 figures, accepted to PASP; minor revision to add two authors and adjust text to match that of the published version. No adjustments to results or conclusion