THE MASS-RATIO OF THE CATACLYSMIC VARIABLE AM HERCULIS

We present far red time-resolved spectroscopy of the cataclysmic variable AM Herculis. We measure the radial velocity semi-amplitude of the secondary component to be 198 +/- 3 km s(-1) and the projected rotational velocity of this star to be 92 +/- 9 km s(-1). Thus we are able to estimate the ratio of component masses to be 0.47 +/- 0.08. We show, however, that these measurements are likely to be biased by ionization of the inner secondary surface by radiation originating close to the shock region above the surface of the primary. Using models of the Na surface distribution on the secondary star, we attempt to produce a less biased orbital parameter solution. These results indicate that the uncertainties in the measured, irradiation-affected parameters are too large to produce a well-constrained, corrected orbital solution with our limited spectral information. However, the method employed to make the irradiation correction has potential to produce accurate binary parameters given improved data.