HEAO 3 discovery of Al-26 in the interstellar medium

A new analysis technique was used with HEAO 3 satellite gamma ray data to quantify the galactic 1809 keV emission. A method of bins was applied in summing for specific scan directions, followed by fitting the source and background components. The 1809 keV line of Al-26 was significant because of the recent discovery that Al-26 was overabundant in meteoritic material and implanted during solar system formation. The HEAO 3 flux indicated a current decay of 3 solar masses of Al-26 per year in the interstellar medium, possibly occurring in red giants and massive main sequence stars. The ratio of the observed Al-26 to the Al-27 flux was similar to that measured in meteorites, which suggests that the ratio is normal for the galactic medium and that no supernova triggered the protosolar nebular collapse.