CE 315: A new interacting double-degenerate binary star

We present spectroscopic observations of object CE 315 revealing a blue con tinuum with strong emission lines. Most of the detected lines are identifie d with He I or He II in emission, with a handful of faint lines of nitrogen . Notable is the complete absence of hydrogen lines. The He lines exhibit t riple-peaked profiles with remarkably broad widths of similar to 2000 km s( -1) (FWZP). The observations show that CE 315 is an interacting binary syst em with an orbital period of 65.1 +/- 0.7 minutes and a mass ratio of 0.022 . We conclude that the most likely scenario for this object is that of an a ccreting similar to0.77 M. white dwarf with a similar to0.017 M. helium whi te dwarf as mass donor.