Far Ultraviolet Rapid HST Photometry of U Gem in Outburst and WZ Sge in Quiescence

Abstract

Until the advent of HST, the detailed temporal behavior of dwarf novae in the UV spectral range was poorly understood. HST, with its combination of high time and spectral resolutions, has begun to open this field. AE Aqr was recently the subject of high time resolution UV spectroscopy with the Faint Object Spectrograph. The authors found AE Aqr’s coherent 33 second oscillation to have a very large amplitude in the UV (Eracleous et al. 1994). We have undertaken two similar time series studies of U Gem and WZ Sge’s UV photometric behaviors, searching for both coherent periodicities which may arise from the rotation of the accreting white dwarf, and quasi-periodic variations.

Based on observations with the NASA/ESA Hubble Space Telescope. obtained at the Space Telescopt Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS5-26555.