Modeling RR Telescopii through the evolution of the spectra

We investigate the evolution of RR Tel after the outburst by fitting the emission spectra in two epochs. The first one (1978) is characterized by large fluctuations in the light curve, and the second one (1993) by a slow fading trend. In the frame of a colliding wind model, two shocks are present: the reverse shock propagates in the direction of the white dwarf, while the other one expands toward or beyond the giant. The results of our modeling show that in 1993, the expanding shock has overcome the system and is propagating in the nearby ISM. The large fluctuations observed in the 1978 light curve result from line intensity rather than from continuum variation. These variations are explained by fragmentation of matter at the time of head-on collision of the winds from the two stars. A high-velocity (500 km s(-1)) wind component is revealed from the fit of the SED of the continuum in the X-ray range in 1978, but is quite unobservable in the line profiles. The geometrical thickness of the emitting clumps is the critical parameter that can explain the short-timescale variabilities of the spectrum and the trend of slow line intensity decrease.