HD 109962: the Most Massive Dwarf NovaquestionMark

HD 109962, a bright F2 star and an ellipsoidal variable, is arecentlyrecognized erupting variable star. Fairly regular outbursts over thepast 5 years suggest it is a dwarf nova. Spectra during the Jan 2006 outburstrevealed strong He II 4686 emission, and the residual spectrum (outburst postoutburst) is that of an accretion disk. The large mass function suggests a totalsystem mass of about 2.3 solar masses, making this one of the most massive dwarfnovae known. The radial velocity curve of the primary suggests either aneccentric orbit or shadowing by an asymmetric disk. Both possibilities areinteresting. We propose to observe for one binary orbit (80 ksec) to study thequiescent Xray emission, study the orbital modulation of the Xray flux, and look for an Xray eclipse truncated!, Please see actual data for full text [truncated!, Please see actual data for full text]