A supernova outbreak is a phenomenon that marks the end of a massive star's life cycle. However, it was thanks to the supernovae that all life appeared on earth, including us and you. So the atoms in your right hand came from the bowels of the long-dead star and the atoms in your left hand – from the bowels of the others. Despite all the poetry and beauty of this phenomenon, a supernova explosion near Earth can cause disaster. Exactly this happened about 2.6 million years ago – the explosion of one of these stars illuminated the sky of our planet from a distance of about 150 light years. A few hundred years later, when the new star had already disappeared from the firmament, cosmic rays reached Earth. Recently, scientists have discovered that this cosmic phenomenon is associated with the mass extinction of animals that roamed the surface of our planet at the time. The study was published in the journal Astrobiology.
According to a press release from the study, the recently documented "megafauna extinction in the ocean" coincides with the arrival of a potentially fatal radiation stream from a supernova explosion near Earth. Scientists believe that this outbreak has led to the extinction of approximately 36% of the species (including megalodon) that live in coastal waters. The researchers believe that the killer radiation reached Earth in the form of cosmic rays, which consist of fast-moving muons – elementary particles with a negative charge, the mass of which is several hundred times the mass of an electron.
Megalodon is a species of extinct shark that we mentioned in one of our materials.
Based on the speed at which muons hit Earth as a result of a supernova explosion, the scientists calculated that the risk of cancer among Homo Sapiens representatives would increase by around 50% if this event occurred in our time. And since high-energy muons can penetrate deep into the water, they could have fatal effects on marine life and cause them to die out massively. Discover cites the study's authors that muons are a few hundred times more massive than an electron and penetrate everywhere. Nowadays, many muons pass through us without causing harm, but about a fifth of the radiation dose received by humans falls on them. But why did scientists decide that the cause of the mass extinction was muons?
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How is a supernova explosion related to the mass extinction of wild animals?
The traces of a supernova explosion were discovered as deposits of the iron 60 isotope – a radioactive iron isotope that, if it had been in the earth at the time it was formed, would have decayed. And researchers recently discovered traces of isotope-60 in samples of the Earth's crust collected in the Pacific, Atlantic and Indian Oceans. The explosion of stars can be the only source of deposits of this isotope in the intestine of our planet. But where did the supernova come so close to Earth?
As the authors of the article write, the sun is in a region that astronomers call a local or local bubble – this is a relatively empty region of interstellar space. Overall, a local bubble is an area of 300 light years that is filled with hot gas and limited to cold. Researchers believe that such bubbles, and there are many of them in our region of the galaxy, have arisen as a result of explosions from supernova stars, the energy of which can sweep everything in their path, and what is left is heated to a bubble to build.
However, scientists do not rule out that a local bubble occurred as a result of the explosion of several supernovae, which also caused the deposition of the iron 60 isotope in the intestine of our planet. In addition, a local bubble may increase the number of radioactive rays – its boundaries could reflect the rays and create a kind of "bath of cosmic rays".
What do you think if you and I had the opportunity to swim in such a radioactive bath, what would that lead to? Share your answer in the comments and with the participants in our telegram chat
In general, the results of the study showed that a supernova that erupted 2.6 million years ago can be associated with the extinction of marine megafauna on the border between the Pliocene and the Pleistocene. At the same time, the organisms living in coastal waters received the greatest amount of radiation, since the damage to the muons decreased with increasing depth.