A model for the X-ray spectrum of the symbiotic nova RR Telescopii.

Pointed ROSAT position sensitive proportional counter (PSPC) observations of the symbiotic nova RR Tel are presented. The PSPC pulse height distribution exhibits a rather soft energy distribution plus few, but significant counts at higher energies. We interprete this as superposition of photospheric flux from the hot component of the symbiotic binary system, and X-rays emitted by a hot plasma, probably shocked by the colliding winds from the two binary components. For modeling the stellar component we use black body emission, as well as line-blanketed non-local thermodynamic equilibrium (NLTE) model atmospheres. Additional constraints for the parameters of the hot star are provided by UV spectra obtained with IUE and VOYAGER. The parameters of the plasma are confined by published EINSTEIN count rates. A stellar atmosphere model with L = 3500 solar luminosity, T_eff = 142000 K, log g = 6.5, and solar abundances, complemented with emission of several times 0.01 solar luminosity by a several 10⁶ K hot plasma reproduces both, UV and X-ray data. For the hot star's atmosphere, any other chemical compositions can be excluded.