Preliminary results from the diffuse x-ray spectrometer

The Diffuse X-Ray Spectrometer (DXS) experiment was flown as an attached Shuttle payload in January 1993 aboard the STS-54 mission of the Space Shuttle Endeavor. DXS consists of two large-area Bragg crystal X-ray spectrometers that cover the 44 - 83 angstroms wavelength range, and are designed to measure the spectrum of the low energy (0.15 < E < 0.28 keV) diffuse X-ray background with roughly 10 eV energy resolution and 15 degree(s) angular resolution. These diffuse X-rays are thought to be generated by a very hot (10⁶ K) component of the interstellar medium that occupies a large fraction of the interstellar volume near the Sun. Astrophysical plasmas near 10⁶ K are rich in emission lines, and the relative strengths of these lines, besides providing information about the physical conditions of the emitting gas, also provide information about its composition, history and heating mechanisms. We present preliminary spectra of the soft X-ray background in the energy range 0.15 < E < 0.28 keV. Spectra were obtained from along a great circle that lies 0 degree(s) - 10 degree(s) north of the galactic plane between galactic longitudes 150 degree(s) and 300 degree(s). The spectra show emission lines, the first direct evidence that the soft X-ray background arises in hot interstellar gas. The spectra seen along the great circle in different resolution elements are different from one another. We fitted a range of models to these spectra, and present preliminary results of these fits.