1994A&A...289..597K

Two pointed ROSAT observations of neutral hydrogen clouds located at very different distances in the general direction of the Draco nebula are presented. These observations offer a unique possibility to study the temperature distribution of the soft X-ray background (SXRB) in detail. The observed anticorrelation of the HI column densities and the soft X-ray count rates is in quantitative agreement with the theoretical absorption cross section of the interstellar matter. Furthermore, soft X-ray spectra give direct evidence for the existence of a two component spectrum of the SXRB. Fits to the X-ray spectra are in agreement with a model consisting of a cooler (T_local≃10^5.85±0.1K) local X-ray emitting plasma in addition to a hotter (T_distant≃10^6.3±0.1K) plasma located beyond the galactic HI layer. The emission measure of the distant plasma is 4-5 times higher than of the local plasma. Therefore this distant plasma contributes significantly to the (1)/(4)keV and (3)/(4)keV diffuse background emission.