A $\widetilde{ \chi}^2$ analysis of standard model accretion disk synthetic spectrum fits to combined $FUSE$ and STIS spectra of V3885 Sagittarius, on an absolute flux basis, selects a model that accurately represents the observed SED. Calculation of the synthetic spectrum requires the following system parameters. The cataclysmic variable secondary star period-mass relation calibrated by Knigge in 2007 sets the secondary component mass. A mean white dwarf (WD) mass from the same study, that is consistent with an observationally-determined mass ratio, sets the adopted WD mass of $0.7M_{ \odot}$, and the WD radius follows from standard theoretical models. The adopted inclination, $i=65{ \arcdeg}$, is a literature consensus, and is subsequently supported by $\widetilde{ \chi}^2$ analysis. The mass transfer rate is the remaining parameter to set the accretion disk $T_{ \rm eff}$ profile, and the $Hipparcos$ parallax constrains that parameter to $\dot{ M}=5.0{ \pm}2.0{ \times}10^{ -9} M_{ \odot} { \rm yr}^{ -1}$ by a comparison with observed spectra. The fit to the observed spectra adopts the contribution of a $57,000{ \pm}5000$K WD. The model thus provides realistic constraints on $\dot{ M}$ and $T_{ \rm eff}$ for a large $\dot{ M}$ system above the period gap.
Categories: astro-ph.SR