We present a spectral analysis of the FUSE spectra of 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 ~ 0.65 and phi ~ 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 maximual, using the codes TLUSTY and SYNSPEC. Using a
single white dwarf spectral component, we obtain a white dwarf temperature of
40,000K, rotating at 100km/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 1.E-10 Msun/yr.In both cases, however, we obtain
that the white dwarf temperature is much higher than previously estimated.Comment: accepted for publication in ApJ, 3 Tables, 12 Figures (including
color figures), 33 pages in present format (possibly 10 pages in ApJ format