The discovery of UV oscillations in WZ SGE

We report the discovery of ~28-s ultraviolet oscillations in the cataclysmic variable WZ Sge. The strength of the oscillations is strongly wavelength-dependent: the oscillation amplitude decreases rapidly from lambda~1500 to ~1250 A. We interpret this decrease as an indication that the spectrum of the oscillations contains a broad Lyalpha absorption line. This implies that the white dwarf photosphere is the origin of the oscillation signal: whether it is due to white dwarf pulsations or magnetically channelled accretion on to a rapidly spinning white dwarf remains unknown.