Speaker
Brian Fields
(University of Illinois)
Description
Supernovae are critical for life in many ways, e.g., their
nucleosynthesis is the dominant cosmic source of heavy elements
essential for planet formation and ultimately for biology. Yet
supernovae take a more sinister shade when they occur closer to home,
because an explosion inside a certain "minimum safe distance" would
pose a grave threat to life on Earth. We will discuss these cosmic
insults to life, and ways to determine whether a supernova occurred
nearby over the course of the Earth's existence. We will then present
recent evidence that a star exploded near the Earth about 3 million
years ago. Radioactive iron-60 atoms have been found in ancient
samples of deep-ocean material, and are likely to be debris from this
explosion. Recent, high-quality data confirm this radioactive signal,
represent a major step forward for this field. We will present
simulations of the supernova impact on the solar system and delivery
of ejecta into Earth's orbit. We will show how sea sediments can be
used for nuclear astrophysics "archaeology": terrestrial
samples of supernova debris allow direct laboratory probes of
nucleosynthesis products from an individual explosion.
Author
Brian Fields
(University of Illinois)
Co-author
Themis Athanassiadou
(University of Illinois)
