26Al All-Sky Map
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This COMPTEL image is taken at energy of 1.809 MeV, which corresponds to the gamma-ray line produced by the radioactive decay of the 26Al isotope. 26Al has a decay time of a million years, and is produced along with other elements in trace quantities at cosmic sites of nucleosynthesis. Therefore, the sky image in these gamma-rays integrates nucleosynthesis events over millions of years and shows the spatial distribution of these events. From the above image we learn that 26Al-producing events are predominantly Galactic sources. Several localized regions appear prominent (Inner Galaxy, Cygnus, Vela), suggesting that massive stars (via their Wolf-Rayet winds and core-collapse supernovae) are the true sources. The insert shows the spectral information captured by COMPTEL. The 26Al line at 1.809 MeV is clearly seen above the large instrumental background. COMPTEL is the first imaging instrument with a spatial resolution of roughly degrees, and thus made possible this all-sky survey of 26Al radioactivity. The Galaxy is transparent to gamma-rays, therefore this image has, for the first time, shown us the locations of nucleosynthesis and massive stars throughout the Galaxy.
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