Far Ultraviolet Spectroscopic Explorer 900-1200 Å Spectroscopy of AM Herculis

Abstract

Spectra of the magnetic white dwarf binary AM Herculis were obtained with the Far Ultraviolet Spectroscopic Explorer during three consecutive spacecraft orbits. These observations were split into 19 spectra of about 5 minutes' duration (0.025P binary phase) partially covering the binary orbit. We report the phase-related changes in the far-ultraviolet (FUV) continuum light curve and the emission lines, noting particularly the behavior of O VI. We discuss the fluxes and velocities of the narrow and broad O VI emissions. We find that the FUV light curve has maximum amplitude at ~1000 Å, although at shorter wavelengths the continuum may be strongly affected by overlapping Lyman lines. Weak, narrow Lyman absorption lines are present. Their velocities do not appear to vary over the observed orbital phases, and their mean value is consistent with the systemic velocity. Based on observations made with the NASA-CNES-CSA Far Ultraviolet Spectroscopic Explorer. FUSE is operated for NASA by Johns Hopkins University under NASA contract NAS 5-3298