When the brightness of the star Betelgeuse decreased dramatically a few months ago, some observers suspected an impending supernova ̵
The life of stars with a mass more than ten times that of our sun ends in a supernova, a colossal star explosion. This explosion leads to the formation of iron, manganese and other heavy elements.
In layers of a manganese crust that are around two and a half million years old, a research team led by physicists from the Technical University of Munich has now confirmed the existence of iron-60 and manganese-53.
“The increased levels of manganese-53 can be viewed as a ‘smoking weapon’ – the ultimate proof that this supernova actually took place,” says first author Dr. Gunther Korschinek.
While a very close supernova could cause massive damage to life on Earth, it was far enough away. It only caused an increase in cosmic rays over several thousand years. “However, this can lead to increased cloud formation,” says co-author Dr. Thomas Faestermann. “Perhaps it is related to the Pleistocene, the Ice Age that began 2.6 million years ago.”
Ultra trace analysis
Typically, manganese occurs on earth as Manganese-55. Manganese-53, on the other hand, usually comes from cosmic dust, such as can be found in the asteroid belt of our solar system. This dust rains continuously on the earth; but only seldom do we perceive larger dust spots that glow as meteorites.
New layers of sediment that build up on the sea floor year after year preserve the distribution of elements in manganese crusts and sediment samples. Using accelerator mass spectrometry, the team of scientists has now detected both iron-60 and increased manganese-53 levels in layers that were deposited around two and a half million years ago.
“This is an investigative ultra-trace analysis,” says Korschinek. “We’re only talking about a few atoms here. However, accelerator mass spectrometry is so sensitive that we can even calculate from our measurements that the exploded star was about 11 to 25 times the size of the sun.”
The researchers were also able to determine the half-life of manganese-53 from comparisons with other nuclides and the age of the samples. The result: 3.7 million years. So far there has only been one single measurement worldwide for this purpose.
Supernova iron found on the moon
G. Korschinek et al., Supernova-Produced Mn53 on Earth, Physical Examination Letters (2020). DOI: 10.1103 / PhysRevLett.125.031101
Provided by the Technical University of Munich
Quote: The stellar explosion near Earth (2020, September 30) was accessed on October 1, 2020 from https://phys.org/news/2020-09-stellar-explosion-earth-proximity.html
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