BEPPOSAX AND ROSAT OBSERVATIONS OF THE SUPERNOVA REMNANT RCW86

We present the first results of a BeppoSAX observation of RCW86, cover ing the south-west part of the remnant (the knee). The spatial analysi s of the LEGS and MECS data confirms that strong variations of the emi ssion hardness exist between the inner and the outer part of the knee. ROSAT data suggest that these variations are not due to absorption ef fects. The Non Equilibrium of Ionization (NEI) spectral analysis of th e LEGS data shows that the emission is characterized by the presence o f a temperature component at kT similar to 2 keV, which, if compared w ith recent ASCA results obtained with a similar analysis, is softer, m ore absorbed, and not heavily metal-depleted. The LEGS data also do no t exclude the presence of a second very soft component (VSC) with kT s imilar to 0.4 keV. The VSC, if real, is to be associated with interact ion of main blast wave with interstellar medium (ISM) inhomogeneities. The NEI spectral analysis of the ROSAT PSPC data confirms the presenc e of the VSC, and yields an estimate of the interstellar absorption an d ionization parameters, but it does not exclude also higher temperatu re components.