GP Com: Helium Cataclysmic Variable and Nitrogen and Neon Monster

GP Com is a heliumstar cataclysmic variable a shortperiod (2792s) semidetached binary consisting of a CO white dwarf primary and a He white dwarfsecondary. GP Com is Xray bright, nearby (d<100 pc), very likely a halo (PopII) object, and has highly anomalous abundances (littletono H, reduced C andO, enhanced N and Ne, and greatly reduced heavy metals). The enhanced Nabundance is hinted at by an existing ASCA spectrum, while the opticallyderived abundances imply that the emission at virgul 1 keV is due not to Fe Lshellemission but to H and Helike Ne (a la the LMXB 4U 162667). We propose a 41.9 ks XMM observation of GP Com to determine the nature (abundances, emission measure distribution, etc.) of the Xray spectrum of this unusual CV. truncated!, Please see actual data for full text [truncated!, Please see actual data for full text]