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Astronomy Colloquium - "When Stars Attack! Near-Earth Supernova Explosions Revealed by Deep-Ocean and Lunar Radioactivity"

Event Type
Seminar/Symposium
Sponsor
Department of Astronomy
Location
134 Astronomy
Date
Sep 12, 2017   3:45 pm  
Speaker
Prof. Brian Fields, U of I
Contact
Rebecca Bare
E-Mail
rsbare@illinois.edu
Phone
217-333-3090
Views
65
Originating Calendar
Astronomy Colloquium Speaker Calendar

Supernovae are major engines of nucleosynthesis, 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 (!). We will review astrophysical 60Fe production sites and show that the data demand that multiple core-collapse supernovae exploded near the Earth over the past ~7 Myr, and explain how debris from the explosion was transported to the Earth as a “radioactive rain.” 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.

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