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September 22, 20224:00 pm – 5:00 pm (CDT)

When Stars Attack! Near-Earth Supernova Explosions Revealed by Deep-Ocean and Lunar Radioactivity (Remote Only)


Brian Fields (University of Illinois Urbana Champaign)


Louis Strigari

Event Details

Supernova explosions are multimessenger particle engines, they
create many of the elements essential for planets and life, and they
play central roles in galaxy evolution. Yet these awesome events
take a sinister shade when they occur close to home, because an
explosion nearby can 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. We will review astrophysical
60Fe production sites and show that the data demand that at least one core -collapse
supernova exploded near the Earth over the past few Myr, and explain how debris from the
explosion was transported to the Earth as a “radioactive rain.” New measurements now
also reveal a second, earlier supernova, and the presence of 244Pu that offers a unique
new probes the production of the heaviest elements in the cosmos. Deep-ocean and lunar
radioactivities thus represent a laboratory for supernova astrophysics, but also with
implications for geology, astrobiology, and possibly terrestrial evolutionary biology.

Video Recording

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