"Based on the minimal distance we expected for a supernova in the Scorpius-Centaurus association at that time, I then did some calculations to explore the potential effects on Earth," said Benitez.
He found that cosmic ray emissions from a supernova could have had a potentially devastating effect on Earth's ozone layer, an upper layer of the atmosphere that absorbs harmful ultraviolet emissions from the sun and other sources.
"This would have produced a significant reduction in phytoplankton abundance and biomass, with devastating effects on other marine populations, such as bivalves," Benitez said.
He emphasized that the theory, while provocative, is consistent with the paleontological evidence, and also with the pattern of movement of the Scorpius-Centaurus group, which would have been at its closest to Earth at that time. He concedes, though, that more evidence will be needed to firmly establish the theory.
In particular, more detailed searches for supernova-produced isotopes in the geological record would show whether there was a tight temporal correspondence between the supernova explosion and the extinction event.
Isotope searches could also offer crucial information about the physical processes involved in supernova explosions.
"People study supernovae using telescopes and supercomputer simulations," said Benitez "In the future, some of the most relevant information in this field may be found in the deep ocean floor."
While the new theory may further heighten concern about human impacts on the ozone layer today, Benitez and Maiz-Apellaniz say there's no need to worry about another supernova in the Scorpius-Centaurus group affecting Earth in the near future.
The next star due to explode in the association, Antares, is now located at a distance of almost 500 light-years, which is too far away to have a significant effect on our planet.
Copyright 2002 AScribe News, Inc.