Ultraviolet Spectroscopy in AM Herculis Stars

We present the UV spectra of fourteen AM Herculis stars and a comparison to computer models. AM Herculis stars are cataclysmic variables with high magnetic fields. The UV spectra for these stars were obtained using the International Ultraviolet Explorer (IUE), with spectral analysis showing an apparent relationship between the strength of the magnetic field and the strength of the UV emission lines. ROSAT observations of a number of AM Her systems reveal a well defined relationship between the white dwarf magnetic field strength and the ratio of the blackbody to Bremsstrahlung fluxes. Using the program CLOUDY, we calculated the output UV spectra obtained from various input simple accretion regions of differing blackbody to Bremsstrahlung flux ratios. The model spectra show a relationship which agrees with that determined from the IUE data.