EUV Absorption Spectroscopy of the DA White Dwarf Star GD 394

The DA white dwarf star GD 394 is one of the coolest to show absorption in the EUV and soft X-ray spectral ranges as a result of the presence of heavy elements in a predominantly H photosphere. We present an EUVE spectrum of this object. The spectrum shows a clear deviation from a pure H model for any acceptable temperature. Indeed, the spectrum and its deviation from pure H models is qualitatively very similar to the spectrum of the hotter DA white dwarf GD 246. Unfortunately, it is not possible at this time to provide a unique interpretation of this spectrum, largely because it was obtained before the dithering technique was implemented to remove fixed-pattern noise. The one clear conclusion, in agreement with EUVE studies of other hot white dwarf stars, is that helium is not the source of the EUV opacity. We also discuss optical and ultraviolet observations of this object, which provide some constraints and some contradictory results pertaining to its temperature.