Implications of the Broad 26A1 1809 keV Line Observed by GRIS

The surprisingly large width of the 1809 ke V gamma-ray line from decay old radioactive Al, recently observed by GRIS (Naya et al. 1996), has profound astrophysical implications. While there may be no apparent, single mechanism that can explain the oberved broadening, wen identify high speed dust grains, extremely hot superbubbles, and a large, low density, gaseous halo in the Galactic center region as the possible origins and iscuss their intriguing revelation of the hot gas content in the ISM