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Published 19:45 IST, August 21st 2020

Supernovae explosion may have caused mass extinction on Earth 359 million years ago

Scientists find that Late Devonian extinction, one of major five in history of the Earth’s existence, might have been caused by Supernovae explosion.

Reported by: Zaini Majeed
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Researchers at the  University of Illinois Urbana-Champaign have discovered that a mass of the exploding stars or the 'supernovae' 65 light-years from Earth might have caused the mass extinction event almost 359 million years ago. In a new study published in the Journal Proceedings of the National Academy of Sciences of the United States, led by astrophysicist Brian Fields, scientists found that the Late Devonian extinction, one of the major five in the history of the Earth’s existence, might have been caused by an explosion from distant stars. The study found that it was the supernova that “coincided with a dramatic drop in stratospheric ozone, possibly due to a global temperature rise” that might have led to the final extinction event.

Supernova explosion could inflict damage by accelerating cosmic rays that can deliver ionizing radiation for up to ∼100 ky, scientists proposed in the research.

We, therefore, propose that the end-Devonian extinctions were triggered by supernova explosions at ∼20pc, somewhat beyond the 'kill distance' that would have precipitated a full mass extinction, they added.

According to the research, the supernovae likely due to core collapses of massive stars are concentrated in the thin Galactic disk where the Sun resides. Therefore, scientists said that the episode mass dying previously accounted for asteroid impacts, climate change, sea-level changes, and large-scale volcanic activity was actually a result of the catastrophic supernovae explosions on the solar system. 

[This Chandra X-ray photograph shows Cassiopeia A (Cas A, for short), the youngest supernova remnant in the Milky Way. Image: © NASA/CXC/MIT/UMass Amherst/M.D.Stage et al.]

[ In this illustration, a white dwarf pulls matter from a companion star. Eventually, this will cause the white dwarf and the star to explode. Image credit: STScI/NASA]

[Gamma Ray burst from the Supernova. Credit: NASA/DOE/Fermi LAT Collaboration, CXC/SAO/JPL-Caltech/Steward/O. Krause et al., and NRAO/AUI.]

Author and astronomer Brian Fields of the University of Illinois at Urbana-Champaign said, “We propose that one or more supernova explosions, about 65 light-years away from Earth, could have been responsible for the protracted loss of ozone.” He added, “Earth-based catastrophes such as large-scale volcanism and global warming can destroy the ozone layer too, but evidence for those is inconclusive for the time interval in question.” Further, the researchers ruled out the Ozone depletion due to any other space event. In the study, they explained that the Astrophysical mechanisms for biosphere damage include “bolide impacts, solar proton events, supernova (SN) explosions, gamma-ray bursts, and neutron star mergers (kilonovae). Bolide impacts, gamma-ray bursts, and solar proton events are essentially impulsive, caused by the supernova explosions.”

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Supernova explosion had a more “lasting impact”

“These events end quickly and are unlikely to cause the long-lasting ozone depletion that happened at the end of the Devonian period,” paper author and astronomer Jesse Miller at the University of Illinois said in the research. Further, he stressed that the supernova explosion had a more “lasting impact” on the Ozone depletion. Researchers predicted that if the exploding star had turned to a nova, causing damaging ultraviolet, X-ray, and gamma-ray radiation, the Earth's ozone layer would have likely lasted up to some 100,000 years. “This is entirely possible. Massive stars usually occur in clusters with other massive stars, and other supernovae are likely to occur soon after the first explosion,” Miller confirmed. 

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(Image Credit: Unsplash/@joelfilip)

19:46 IST, August 21st 2020