Astrophysicist Sean Bishop of the Technical University of Munich found traces of a supernova in the most unobvious place on the ocean floor. According to an article published in the scientific journal Proceedings of the National Academy of Sciences, a find in the form of a fossil submerged in the muddy bottom of the Pacific Ocean does contain supernova signs.
Hoping to find traces of a special isotope of iron produced by a supernova about 2.2 million years ago, Bishop studied the ocean floor for several years and studied the fossils of an ancient bacterium. The scientist shared his first promising discoveries at a physicist conference back in 2013. Now, the early findings were confirmed, as reported by the article of the scientific journal Proceedings of the National Academy of Sciences (PNAS).
“The signs are indeed present,” says Bishop.
The isotope that interested the scientist is iron-60 (60Fe), one of the heavy elements created by the explosion of supernovae and ejected into space. Since 60Fe has a short half-life, this element cannot be present on Earth, but its traces were nevertheless found in the iron-manganese crust of the ocean floor.
Ancient bacterium and its magnetite chains
Bishop considered the best place to search for the residual micro-deposits of an ancient bacterium, which scientists found in sediment core samples taken from the ocean floor. As early as 1963, Italian microbiologist Salvatore Bellini noted that this bacterium can determine the direction of the North Pole. In other words, these bacteria can sense magnetic fields that help them move to more suitable environments with low oxygen content. Inside these bacteria there are chains of magnetite crystals, therefore in the scientific environment they are called “magnetotactics”. Back in 2013, Scientific American wrote:
“Bishop believes that once the remnants of a supernova could pass through the atmosphere of the Earth, quickly oxidize and crumble into tiny nanooxides. With rapid oxidation, they turned to rust, which eventually plunged into the ocean floor, becoming food for bacteria. When bacteria died, an accumulation of chains of magnetite crystals and a trapped 60Fe isotope occurred. Therefore, any traces of 60Fe found in sediments are a kind of biogenic signature of the supernova explosion that occurred, which was sealed in these sediments. ”
It is very difficult to detect these traces, but using accelerator mass spectrometry (AMS), Bishop was able to analyze every single bacterium that was contained in core samples taken from the bottom of the Pacific Ocean. After that, one by one, he calculated the number of contained 60Fe atoms. The information obtained indicated that the isotopes could have belonged to a supernova that exploded about 2.2 million years ago. Moreover, the scientist even picked up several suitable candidates in the cluster of Scorpio - Centauri.
Bishop's discovery inspired Anton Wallner of the Australian National University to gather an international team of scientists and conduct his own research, in which specialists wanted to find even more traces of the 60Fe isotope. In a series of articles in Nature magazine in April of this year, scientists reported that they really identified evidence of a series of supernova explosions that occurred about 7 million years ago, whose traces were discovered on Earth. The nearest supernova explosion occurred in a nearby star cluster at a distance of about 326 light-years from us.
Thanks to the results of Bishop’s work and new research by an international team of scientists, we have strong evidence that supernovae could reach Earth. At least one of the explosions could have happened during the Pleistocene era, the period of global cooling. It should be noted that scientists had previously expressed suspicions that supernova explosions could affect the Earth’s climate (mainly by burning the ozone layer). Therefore, it is possible that one of these explosions could be the cause of the very Pleistocene epoch.
“We have no direct evidence about the link between the supernova explosions and the changes that occurred to the Earth as part of its history,” says Adrian Mellott of the University of Kansas (USA).
"But some hints are still there."
The article is based on materials .
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