Discovery of a large mass of iron in a type I supernova.

The authors have discovered ≡0.3 M_sun; of iron in the type I supernova 1983n in the galaxy M83 about one year after explosion. This is the first time that a massive quantity of iron has been directly and unambiguously detected in a supernova. It was accomplished by the observation of strong [Fe II] line emission in the infrared at 1.644 μm from the optically thin ejecta. This result was predicted by the ⁵⁶Ni-⁵⁶Co-⁵⁶Fe radioactive decay scenario, and provides strong support for its credibility.