1994A&A...288..204B

We present high-speed UBVR-photometry and time-resolved spectroscopy of the X-ray source 1H1752+081. The light curves are characterized by a double eclipse repeating at the orbital period of 112.97 min. and an orbital hump occurring between eclipse phases φ≃0.50 and φ≃0.85. The spectra show strong Balmer lines and the lines of HeI and HeII in emission. The line profiles are characterized by a time-variable broad base component and superposed to them (best seen in Hα and Hβ) a narrow component whose variation is phase-shifted with respect to the base component. Our observations are consistent with 1H1752+081 being a cataclysmic binary of the AM Her subtype observed in a high state. Eclipse analysis and measurement of the radial velocity amplitude of the narrow component of Hα allow estimating the physical parameters. The mass of the white dwarf is M₁≃(0.9±0.1)M_☉, the best estimate of the secondary mass M₂≃0.185M_☉, but values in the range 0.1M_☉<M₂< 0.25M_☉ cannot be ruled out. The parameters are consistent with what one expects from theory for an AM Her star close to the 114 min. period spike, i.e. with the secondary being close to the main sequence and M₁≃0.7M_☉.