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B.W. Greeley, W.P. Blair (JHU), K.S. Long (STScI)
Magnetic cataclysmic variables are cataclysmic variables in which the magnetic field of the white dwarf affects the accretion of material from the red dwarf star. Using the Berkeley Extreme Ultraviolet Spectrometer during the ORFEUS II space shuttle mission, we obtained FUV spectra of the three magnetic CVs AE~Aqr, BY~Cam, and FO~Aqr over the wavelength region from 912-1218 Å.
The spectra of AE Aqr and BY Cam indicate that these objects have anomalous abundances. Both of these objects show strong emission from \ion{N}{3}~\lambda991, but lack emission from \ion{C}{3}~\lambda977 and \ion{C}{3}~\lambda1176. This implies that the carbon to nitrogen abundance ratio in the accreting material is subsolar. For the polar BY Cam, whose slight asynchronism suggests a recent nova outburst, there is also a lack of emission from \ion{O}{6}~\lambda\lambda1032,1038, which may indicate a depletion of oxygen as well. The enhancement of nitrogen relative to carbon is typical of abundances in nova ejecta, suggesting that these two objects may have undergone nova eruptions in the past.
Support for this work is provided by NASA grant NAG5-6732 to the Johns Hopkins University.
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