Dramatic Spectral Evolution of WZ Sge during the 2001 Superoutburst

Abstract

We spectroscopically observed WZ SGE in 11 nights during the 2001 superoutburst. The feature of the spectra dramatically varied from at the outburst maximum through during the rebrightening phase.WZ SGE is the prototypical star of WZ SGE-type stars, a small class of SU UMa-type dwarf novae. WZ SGE stars have unusual characteristics of quite large outburst amplitudes up to ~8 mag, extraordinary long recurrence cycles of the outbursts (≥10 years), no (or only a few) normal outbursts.