CE-315 : A New Interacting Double-degenerate Binary Star

Abstract

We present spectroscopic observations of object CE-315 revealing a blue continuum with strong emission lines. Most of the detected lines are identified 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 triple-peaked profiles with remakably broad widths, of about 2000 km/s (FWZP). The observations show that CE-315 is an interacting binary system 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 accreting 0.77 solar mass white dwarf with a 0.017 solar mass helium white dwarf as mass donor.