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Israeli Scientists: Star Collision Caused Dinosaur Extinction

December 2, 1996

JERUSALEM (AP) _ Israeli scientists have a new theory on why the dinosaurs became extinct: cosmic radiation that bombarded the Earth following the collision of two neutron stars.

Physicists from the Space Research Institute at the Technion University in Haifa theorize that the mass extinction 65 million years ago was caused by the merging of twin stars near the Earth inside the Milky Way galaxy.

This collision created a deadly wave of cosmic radiation that destroyed the protective layers of the Earth’s atmosphere, frying vegetation and obliterating most animal life, the researchers say.

``The study is actually an attempt to solve the biggest murder case in the history of life on Earth,″ said Arnon Dar, a physics professor at the Technion, who with colleagues Nir Shaviv and Ari Lior is submitting the theory for publication in a scientific journal.

There have been several theories that astral radiation caused mass extinctions.

David N. Schramm, an astrophysicist at the University of Chicago, suggested last year that exploding stars called supernovas could have caused another mass extinction _ the most severe in Earth’s history _ that killed 95 percent of all life 225 million years ago.

But Dar said supernovas could not have caused all six mass extinctions that swept over the Earth in the last 650 million years _ one about every 100 million years.

``The rate of supernova explosion is not great enough to explain the 100 million year extinctions,″ Dar said. ``But the merging of neutron stars could be responsible.″

Twin stars merge every day somewhere in the universe, producing radiation in the form of gamma and cosmic rays that strike the Earth’s atmosphere. Usually, the stars are too far away to do any damage and the radiation is harmlessly absorbed by the ozone layer.

But occasionally _ about every 100 million years by Dar’s estimate _ twin or binary stars collide close to Earth, producing devastating effects.

Dar’s theory is ``a credible idea,″ Schramm said. ``We do know there is at least one known pair of neutron stars (near Earth) that are spiraling closer together and will indeed collide.″

But that collision, he said, is at least 100,000 years away.

The dinosaurs’ demise has been the subject of hot debate in scientific circles. Dar discounts the prevailing theory _ supported by Schramm _ that an asteroid strike in Chicxulub in Mexico’s Yucatan was to blame.

Chicxulub is home to a crater more than 100 miles wide that could have been formed by a blast with the explosive power of 100 to 300 megatons of TNT. The theory holds that the asteroid crash created a huge explosion that cast enough dust and rock into the atmosphere to block out the sun, turning the Earth cold and inhospitable to all but the hardiest organisms.

Dar said this theory does not explain the great leap in biodiversity following the mass extinctions. He contends the vast amount of radiation produced by a neutron star collision explains why the number of animal and plant species increased so quickly after mass extinctions.

Those animals that survived _ because of their hardiness or lack of radioactive exposure _ would have produced a greater number of genetic mutations, Dar said.

Dar is now trying to determine which twin stars in the Earth’s vicinity are likely to collide and potentially bring on the next mass extinction.

``In principle, we could predict almost precisely how long it will take before they merge in this lethal way,″ he said.

Meanwhile, both Schramm and the Israeli scientists are continuing to look for evidence of irradiated minerals in the Earth’s geologic layers, signs of either a supernova or neutron star collision.

``I think the real test will be if we can find these isotopic anomalies,″ Schramm said. ``Unless we find those, we’re missing the smoking gun.″

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