2003MNRAS.339..148C

We analyse the optical spectra and the ultraviolet (UV) spectral evolution of the jets and of the HII region inside the R Aquarii binary system using the code suma, which accounts for shock and photoionization consistently. The temperature of the hot star is 80000 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 1980 November 8 to 1991 May 26 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 against the fit of the continuum spectral energy distribution. It is found that a blackbody temperature of 2800 K reproduces the radiation from the red giant. A blackbody emission component corresponding to 1000 K is emitted by dust in the surroundings 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 approximately 2x10¹⁵ cm from the internal system, while the distance of the SW jet bulk is ∼6x10¹⁴ cm. The distance of the reverse shock from the hot source in the internal region is ≤9x10¹³ cm.