  We analyse the optical spectra and the UV spectral evolution of the jets and
of the HII region inside the R Aquarii binary system by the code SUMA which
consistently accounts for shock and photoionization. The temperature of the hot
star results 80,000 K as for a white dwarf. We find that the shock velocity in
the NE jet increased between 1983 and 1989. The spectral evolution between 1989
and 1991 of the SW jet indicates that a larger contribution from low
density-velocity matter affects the 1991 spectra. The evolution of the UV
spectra from 8/11/1980 to 26/5/1991 in the HII region indicates that the
reverse shock is actually a standing shock. The results obtained by modelling
the line spectra are cross-checked by the fit of the continuum SED. It is found
that a black-body temperature of 2800 K reproduces the radiation from the red
giant. A black-body emission component corresponding to 1000 K is emitted by
dust in the surrounding of the red giant. Model calculations confirm that the
radio emission is of thermal origin. We found that the NE jet bulk emission is
at a distance of about 2 (15) cm from the internal system, while the distance
of the SW jet bulk is about 6 (14) cm. The distance of the reverse shock from
the hot source in the internal region is < 9 (13) cm.
