X-ray observations of the first known eclipsing ultra-compact binary system

Ultracompact systems are a group of stars in which a white dwarf accretes froma hydrogen deficient companion in a very short period binary (565 mins). Theyallow us to observe accretion flows of almost pure helium. The evolution ofthese systems is thought to be driven by gravitational radiation. Detailedpredictions depend crucially upon parameters such as the component masses andmass transfer rate. With the recent discovery of the first eclipsing AM CVn wenow have the opportunity to determine all the key parameters of one system. Thisproposal aims to measure its overall spectral energy distribution, which isimportant for determining its overall luminosity and mass transfer rate; tolocate the sites of the Xray and UV emission and map the extent of the accretion disc using eclipse mapping. truncated!, Please see actual data for full text [truncated!, Please see actual data for full text]