The hot wind in the symbiotic nova AG Pegasi.

The nature of the hot radiation source in symbiotic systems is still controversial. In AG Peg, the hot component went into a thermonuclear outburst after a probably long phase of mass accretion from the cool giant companion. This outburst has been lasting for more than 150 years. During most of this phase the hot compact component has been losing mass through a stellar wind. We show that this wind can be traced in UV spectra, and we present a simple method for estimating the mass loss rate, which is of the order of 10^-7^M_sun_/yr at a velocity of ~900km/s. The strength of the wind has diminished by a factor of 5 during the last decade, and the outbursting star might soon reach its pre-outburst state. The cool giant companion also loses mass at a similar rate, leading to a collision region between the two stars. Evidence for such a collision zone could be obtained from X-ray observations or from radio images with high spatial resolution, showing directly the topology of the nebular emission region.