THE ROSAT SPECTRUM OF THE SYMBIOTIC NOVA AG PEGASI - EVIDENCE FOR COLLIDING WINDS

Pointed ROSAT PSPC observations of the symbiotic nova AG Peg are prese nted and analyzed. A basic analysis shows that the X-rays are emitted by a hot - probably shock-heated - plasma with a temperature of a few MK. We suggest that we are facing the first definite observation of co lliding winds in a symbiotic binary system. Using a one point model, w e derive for the emitting plasma a characteristic temperature of 3.5 . 10(6) K, a luminosity of 0.01 L(.)(bol), and an emission measure of 1 .5 . 10(54) cm(-3). A 2D hydrodynamic simulation resting on published system parameters reproduces these results.