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R.T. Hamilton, E.M. Sion (Villanova University)
We have analyzed the IUE archival spectra of two dwarf novae systems in outburst with newly determined trigonometric parallaxes, VY Aquari, an SU Uma system below the period gap, and RU Peg, a U Gem system above the period gap. For VY Aquari, the best fitting optically thick steady-state accretion disk model yields an accretion rate of 10-9 {M\odot}/yr and a scale factor distance from the best fitting disk model of 92 pc. This is in excellent agreement with the parallax distance of 97 pc obtained by Thorstensen (2003, AJ, 126, 3017). The white dwarf mass and disk inclination used in this best fit are 0.55 M\odot and 41\circ respectively. For RU Peg, our best fitting steady state optically thick disk model yields an accretion rate of 10-9 M\odot/yr with a white dwarf mass of 1.21 {M\odot} and an inclination of 41\circ. This accretion rate is nearly a factor of 10 lower than that of Patterson (1984, ApJS, 54, 443). The resulting scale factor distance gives excellent agreement with the parallax distance of 282 pc by Harrison et al. (2004, AJ, 127, 460). However, there is a significant deviation from a steady-state disk flux distribution in the observed spectrum longward of 1600Å. Implications of these finding will be discussed. \newline \newline We acknowledge support of this research by NSF Grant AST99-01955 and NASA ADP Grant NAG5-11182
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Bulletin of the American Astronomical Society, 36 #2
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