Synthetic Spectrum Constraints on a Model of the Cataclysmic Variable QU Carinae

Abstract

Neither standard model SEDs nor truncated standard model SEDs fit observed spectra of QU Carinae with acceptable accuracy over the range 900-3000 A. Nonstandard model SEDs fit the observation set accurately. The nonstandard accretion disk models have a hot region extending from the white dwarf to -->R = 1.36RWD, a narrow intermediate-temperature annulus, and an isothermal remainder to the tidal cutoff boundary. The models include a range of $d{M}$ --> values between -->1.0 × 10−7 and -->1.0 × 10−6 M☉ yr−1 and limiting values of MWD between 0.6 and 1.2 M☉. A solution with -->MWD = 1.2 M☉ is consistent with an empirical mass-period relation. The set of models agree on a limited range of possible isothermal region Teff values between 14,000 and 18,000 K. The model-to-model residuals are so similar that it is not possible to choose a best model. The Hipparcos distance, 610 pc, is representative of the model results. The orbital inclination is between 40° and 60°.