Did star cluster's death rays zap Earth?

摘要

Ablast of radiation from a passing star cluster could turn out to be the cause of a mass extinction on ancient Earth. In 2003, a team led by Adrian Melott of the University of Kansas in Lawrence suggested that a gamma-ray burst within a few thousand light years of Earth triggered a mass extinction 440 million years ago. But proof has been elusive. Because these bursts occur when a single star explodes or two stellar corpses merge, there is little left to identify the culprit.