Berlin, Jan 22: A gamma-ray burst may have caused an intense blast of high-energy radiation that hit the Earth in the eighth century, report scientists from the Astrophysics Institute of the University of Jena, Germany.
In 2012, scientist Fusa Miyake announced the detection of high levels of the isotope Carbon-14 and Beryllium-10 in tree rings formed in 775 CE, suggesting that a burst of radiation struck the Earth in the year 774 or 775.
Carbon-14 and Beryllium-10 form when radiation from space collides with nitrogen atoms, which then decay to these heavier forms of carbon and beryllium, the journal Monthly Notices of the Royal Astronomical Society reports.
The earlier research ruled out the nearby explosion of a massive star (a supernova) as nothing was recorded in observations at the time and no remnant has been found, according to an Astrophysics Institute statement.
But Valeri Hambaryan and Ralph Neuhuser, of the Astrophysics Institute, have another explanation, consistent with both the carbon-14 measurements and the absence of any recorded events in the sky.
They believe the gamma ray burst originated in a system between 3,000 and 12,000 light years from the Sun.
They suggest that two compact stellar remnants, i.e. black holes, neutron stars or white dwarfs, collided and merged together.
When this happens, some energy is released in the form of gamma rays, the most energetic part of the electromagnetic spectrum that includes visible light.