ULTRACAM photometry of the eclipsing cataclysmic variable OU Vir

ABSTRACT We present high-speed, three-colour photometry of the faint eclipsing cataclysmicvariable OU Vir. For the first time in OU Vir, separate eclipses of the white dwarf andbright spot have been observed. We use timings of these eclipses to derive a purelyphotometric model of the system, obtaining a mass ratio of q = 0.175 ± 0.025, aninclination of i = 79 ◦ .2±0.7 and a disc radius of R d /a = 0.2315±0.0150. We separatethe white dwarf eclipse from the lightcurve and, by fitting a blackbody spectrum toits flux in each passband, obtain a white dwarf temperature of T = 13900±600 K anda distance of D = 51±17 pc. Assuming that the primary obeys the Nauenberg (1972)mass-radius relation for white dwarfs and allowing for temperature effects, we also finda primary mass M w /M⊙ = 0.89 ± 0.20, primary radius R w /R⊙ = 0.0097 ± 0.0031and orbital separation a/R⊙ = 0.74±0.05.Key words: binaries: close – binaries: eclipsing – stars: dwarf novae – stars: individ-ual: OU Vir – novae: cataclysmic variables