Gamma rays from the decay of 26Al: evidence for the explosion of a supermassive star

The possibility is investigated that a supermassive star (M >∼ 5.105 Solar mass) exploded near the galactic center about 106 years ago leaving several solar masses of 26Al. It is shown that such an event is the most natural explanation of the recently observed 1.8 MeV 26Al gamma ray line flux from the galactic center. Our model predicts that at least 3 Solar mass of 26Al are produced in the explosion of a 5.105 Solar mass star if the initial metallicity is roughly three times the solar value. First preliminary results obtained from a hydrodynamic simulation are presented showing that several 105 years after the explosion most of this matter is still concentrated in a narrow ring (R ≅ 40 pc, D ≅ 8 pc) in the galactic plane