We present a spectral analysis of the Far Ultraviolet Spectroscopic Explorer ( FUSE ) spectra of the eclipsing double-line spectroscopic binary EM Cygni , a Z Cam DN system .
The FUSE spectrum , obtained in quiescence , consists of 4 individual exposures ( orbits ) : two exposures , at orbital phases \phi \sim 0.65 and \phi \sim 0.90 , have a lower flux ; and two exposures , at orbital phases \phi = 0.15 and 0.45 , have a relatively higher flux .
The change of flux level as a function of the orbital phase is consistent with the stream material ( flowing over and below the disk from the hot spot region to smaller radii ) partially masking the white dwarf .
We carry out a spectral analysis of the FUSE data , obtained at phase 0.45 ( when the flux is maximal ) , using synthetic spectra generated with the codes TLUSTY and SYNSPEC .
Using a single white dwarf spectral component , we obtain a white dwarf temperature of 40 , 000 \pm 1000 K , rotating at 100 km/s .
The white dwarf , or conceivably , the material overflowing the disk rim , shows suprasolar abundances of silicon , sulphur and possibly nitrogen .
Using a white dwarf+disk composite model , we obtain that the white dwarf temperature could be even as high as 50,000K , contributing more than 90 % of the FUV flux , and the disk contributing less than 10 % must have a mass accretion rate reaching 10 ^ { -10 } M _ { \odot } /yr .
The single white dwarf model fits the absorption lines better than the white dwarf+disk model , but the white dwarf+disk model fits better the continuum in the shorter wavelengths .
In both cases , however , we obtain that the white dwarf temperature is much higher than previously estimated .
We emphasize the importance of modeling the spectra of EM Cyg around phase \phi < 0.5 , when the white dwarf and disk are facing the observer , and we suggest that the discrepancy between the present analysis and previous spectral analysis might be due to the occulting effect of the stream veiling the white dwarf and disk .