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Physics Colloquium Series: Professor Brian Fields
(Physics Lecture Series) University of Illinois Urbana-Champaign, Department of Physics
“When Stars Attack! Near-Earth Supernova Explosions Revealed by Deep-Ocean and Lunar Radioactivity”
Supernova explosions dramatically announce the deaths of massive stars via spectacular outbursts of photons and neutrinos. Supernovae are also particle accelerators, and create many of the elements essential for life. Yet these awesome events take a sinister shade when they occur close to home, because an explosion very nearby would pose a grave threat to Earthlings. We will show how radionuclides produced by supernovae can reveal nearby events in the geologic past, and we will highlight isotopes of interest. In particular, geological evidence for live 60Fe has recently been confirmed globally in multiple sites of deep-ocean material, in cosmic rays, and in lunar samples. Deep-ocean and lunar 60Fe measurements thus represent a new tool for astronomy and astrophysics, but also with implications for geology, astrobiology, and possibly terrestrial evolutionary biology.