Scientists from the United States and Brazil have hypothesized that a supernova exploded 2.6 million years ago at a distance of 50 parsecs (163 light years) from Earth, causing the mass extinction of animals at the end of the Pliocene. According to Adrian Melott of the University of Kansas, large organisms such as the megalodon could have disappeared from heavy charged particles because of the "rain". The article was published in the journal Astrobiology.
Researchers have demonstrated that rocks dated 2.6 million years ago have a peak in the radioisotope iron-60, whose nuclei hit the Earth in the form of cosmic rays. The amount of radioactive material can be used to judge the intensity of secondary cosmic rays - the downward fluxes of particles (muons) that arise in the atmosphere when high-energy cosmic particles interact with it. According to scientists, muon radiation penetrated into the depths of the ocean by one kilometer and exceeded background values. Representatives of the marine megafauna received high doses of radiation throughout their lives.
Scientists do not know for sure whether the cosmic rays were caused by a single supernova or a series of explosions, but there is evidence that there could be several supernovae. The solar system sits on the edge of the Local Bubble, a region of rarefied hot gas that spans 300 light years. It is believed that it was formed by supernovae that erupted 10-12 million years ago, but the cosmic radiation they emitted could bounce off the walls of the bubble and irradiate the Earth for the next millions of years.
