A team of researchers led by Professor Brian Fields hypothesizes that a supernova is about 65 … [+]
An ancient extinction event about 359 million years ago in Earth’s past was probably triggered by incoming cosmic rays from a supernova that was only 65 light-years away. Or so says a new paper just published in The procedures of the National Academy of Sciences (PNAS).
The supernova lay just outside the “cooling distance” at which incoming radiation from the event would have gone down a full mass extinction, the authors note. That, earth-life at the end of the so-called Devonian-Carboniferous Boundary missed an upright global extinction. But cosmic rays from this massive predecessor of this supernova —— suffering a nuclear explosion and a subsequent explosion —— mastered life here on earth by erasing much of the earth’s protective ozone layer. That is, the layer of stratospheric ozone that normally protects the earth’s surface from harmful solar ultraviolet (UV) radiation.
“A supernova would have to lead to extinction patterns similar to ultraviolet exposure due to ozone depletion,” said Brian Fields, a professor of astronomy at the University of Illinois at Urbana-Champaign and the paper’s lead author. “[This] would emit radiation to the surface of the earth up to hundreds of meters due to high-energy muzzle particles that have to hit the earth intensely. ”
It marks the end of the late Devonian Period, which saw a prolonged decline in biodiversity eventually culminate in events before extinction, the authors say. In fact, the recent extinction event may have been accompanied by a dramatic drop in stratospheric ozone, possibly due to a global temperature rise, they note. An associated increase in ultraviolet-B (UV-B) radiation could have done to trigger an elevation in extinction levels and cause direct genetic damage to the planet’s existing flora and fauna, the authors say.
The Devonian-Carboniferous boundary rocks contain hundreds of thousands of generations of plant spores that appear to be sunburned by ultraviolet light – evidence of a long-lasting event of ozone depletion, states the University of Illinois at Urbana-Champaign, leading the study. The idea is that one or more supernovae lying on the thin disk of our galaxy could be responsible for this prolonged ozone loss.
From where in the air did the supernova actually originate?
Researchers have no clue, because no matter where the supernova lay in the sky, its outgoing cosmic rays would be removed and occupied by the magnetic field of our galaxy, Adrian Melott, a physicist at the University of Kansas and one of ‘ e ko authors, told me. This would mean that the cosmic rays of the supernova came in a completely different direction (as directions) than from where they were generated.
Artistic depiction of early Devonian land flora.
The authors note that the discovery of one of the long-lived, radioactive isotopes Plutonium-244 and Samarium-146 in the rocks and fossils deposited at the time of extinction, would confirm a supernova origin. This is because no isotope is yet occurring naturally on Earth today, and a cosmic explosion would be necessary here.
But could there be other astrophysical causes for such extinctions?
Other astrophysical causes of ozone depletion, such as meteorite impact, solar flares and gamma-ray bursts end rapidly and are likely to cause the prolonged ozone depletion that occurred at the end of the Devonian period, states the University of Illinois at Urbana. – Campaign.
Indeed, the authors do not rule out damage caused by multiple supernova explosions in this time frame, because massive stars normally occur in clusters with other massive stars. And subsequent supernovae can often be triggered by the first one leaving in a stellar cluster.
Where and how is the best place to look for the narrative isotopes to prove this hypothesis?
Certain geological sites in Vietnam, Poland, the Montagne-Noire region of France, Italy, the Czech Republic, and perhaps Australia, said Bruce Lieberman, a paleobiologist at the University of Kansas and one of the paper’s co-authors .
Plutonium would probably have been included in fossil bones and shells from the Devonian period, Fields says. But it remains unclear what stellar explosions make plutonium, and it may well be that many supernovae do not make it at all, he says.
This would mean that a ‘lack’ of discovered Plutonium-244 would unfortunately be dubious.
“Maybe there was no supernova at all, but maybe there was one and it didn’t make plutonium,” Fields said.
.
