Violent supernovae may have caused two of Earth’s greatest mass extinctions that have never been fully explained, according to a theory presented in new research.
During the final stages of the life of a gigantic star, its agony culminates in a powerful thermonuclear explosion – a supernova – which typically destroys the celestial object, releasing material and radiation.
A team of researchers related star explosions close to at least one, possibly two, mass extinctions after calculating the stars’ supernova rates closest to the sun-within 65 light years-over the last 1 billion years.
The work was part of a wider survey of rare and massive stars of type O and B, which are relatively short -lived, using data from the European space agency’s Gaia space telescope.
Calculations have suggested that 2.5 supernovae can affect land somehow every 1 billion years, equivalent to one or two in the last 500 million years during which life has evolved on the planet.
The rate is lower than previously thought, said Nick Wright, co-author of the study published Tuesday (18) in the magazine. This finding led Wright and his co -authors to connect the cosmic phenomenon with mass extinctions on Earth. Cataclismic events have occurred five times in the last 500 million years, eliminating most species of water and earth in a relatively short geological interval.
“It’s much more plausible to think that this could be an effect that could affect extinction events,” said Wright, professor of physics and astrophysics and Ernest Rutherford Fellow at Keele University in the United Kingdom.
The findings highlight how colossal stars can both create and destroy life, said the main author of the study, Alexis Quintana.
“Supernova explosions bring heavy chemical elements to the interstellar environment, which are then used to form new stars and planets,” said Quintana, former Postdoctoral Research in Keele and currently at the University of Alicante, Spain, in a statement. “But if a planet – including Earth – is located very close to this type of event, it can have devastating effects.”
In the study, the researchers did not provide evidence that a supernova caused. Instead, the team raised the hypothesis that a star explosion may have been a potential factor in the late Devonian extinction event 372 million years ago and another at the end of the late Ordovician 445 million years ago. The team suggested that a supernova may have destroyed the ozone layer that protects the land from harmful radiation, resulting in a chain of events that could cause mass extinction.
During the Devonian geological era, life prospered on Earth for the first time, but the first terrestrial plants and animals transition from water to the earth were eliminated, along with armored fish and other marine species. A cataclysmic change at the end of Ordovician led to the disappearance of about 85% of species at a time when life was mainly limited to seas.
“Its connection with these mass extinctions, especially late ordovician, is because a suggested consequence of such an explosion near Earth would be the glaciation, which we know then. So, it is an open hypothesis, but there is no evidence,” said Mike Benton, professor of vertebrate paleontology at the University of Bristol, United Kingdom, which was not involved in the research.
“I would like to see a calibration of such historical events to show that one actually happened at the same time as mass extinction in question-we have these reasonably well dated geological events, but we need somehow to date deep supernova explosions,” Benton said by email. He is the author of “Extinction: How Life Survives, Adaptits and Evolves”.
Paul Wignall, professor of paleoenvironment at the University of Leeds, UK, called the research interesting and said it was not the first time that the concept of an extinction caused by Supernova emerged. What is necessary, he said, is tangible evidence that extinctions coincided with supernoves.
“This could come from the exotic elements originating from the explosion and present in minimum quantities in the sedimentary record.”
Heavenly events caused at least one mass extinction, according to scientific evidence. An asteroid the size of a city has hit the Earth on the coast of what is now Mexico on a fateful day 66 million years ago, condemning dinosaurs and many other species to extinction.
Researchers first identified the cause of the ending of the Cretaceous end by the discovery of the “iridia anomaly” – a 1 -centimeter -rich -thick sedimentary rock layer, a rare element on the earth’s surface, but common in meteorites. A study describing the discovery was published in June 1980.
Initially received with skepticism, the anomaly of Irídio was found in increasing places around the world. A decade later, researchers identified a 200 -kilometer width crater on the coast of the Yucatan Peninsula in Mexico.
“It was the enrichment of iridio in the Cretaceous/Paleogen border sediments that was the highly convincing” thorough proof “for the extinction of dinosaurs when the idea was first published in 1980. Supernova theory needs its irodio equivalent, perhaps iron-60 or plutonium?” Said Wignall by email, referring to elements that could be a marker of a supernova.
Iron-60 is a radioactive variant of iron that is not abundant on Earth, but is produced in large quantities in supernova explosions. Wright also said that it may be possible to measure ozone depletion in rocks and sediments.
Recent studies on mass extinction events have shown that it was usually a series of consequence events, often triggered by large -scale volcanic eruptions that were progressively worsening, Wignall added.
“It’s hard to see how a supernova would fit such a scenario,” he said. “At first, before things were very bad or at peak when things were wrong?”
Wright said the goal of his team’s work was to draw attention to the new supernova scale that the researchers had identified. “I think there will be a lot of people who will say, rightly, that we do not know what caused these extinction events. And then there may be some who say we are speculating too much. What we want to just draw attention to the numbers.”
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