2020-08-26

Scientists have discovered deeper secrets in the”dust bath” of Earth’s supernova

By yqqlm yqqlm

According to foreign media reports, scientists speculate that the Earth may have been”drifting” in the remains of a huge supernova explosion for the past 33,000 years. They went deep into the ocean to find evidence of the most mysterious known substance. Scientists have found samples of iron-60 on the seafloor, a radioisotope produced by supernovae, a faint reminder of dying stars.

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The radioactivity of iron-60 makes it a natural time recorder. Since it completely decays in 15 million years, scientists can be sure that any sample found on Earth–or the samples found deep in the Earth’s oceans–has arrived in a relatively recent history.

This is what Anton Wallner of the Australian National University and a team of physicists are hoping for when looking for signs of this isotope, which may have been collected when the earth moved in the universe. Deep-sea sediment samples from two different locations were run through the mass spectrometer at the ANU Heavy Ion Accelerator facility. The age of each sample can be traced back to 33,000 years ago.

Sure enough, the sample contains iron-60. Although the content is very low, its distribution is still consistent with our planet’s recent transition through the local interstellar cloud (LIC). This means that the gas and dust that make up LIC may have been produced by a supernova after a long time.

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However, in the process, scientists stumbled upon a mystery. Although iron-60 exists and coincides with the recent movement of the earth, it also extends to farther places through the sample. In fact, over the entire 33,000-year period spanned by each sample, signs of this isotope were fairly consistent, rather than peaking when the solar system first transitioned to LIC.

This raises the question of the source of iron-60 in space, not to mention if it was not a by-product of past supernovae, then what caused this cloud. Its inherent natural dating potential in radioactive decay provides a narrow window to determine possible origins—at least in astronomy.

“Recent papers indicate that iron-60 trapped in dust particles may rebound in the interstellar medium,” Wallner emphasized. This may indicate that the isotopes measured now can actually be traced back to earlier supernovae. Therefore,”we measured some kind of echo”, the nuclear physicist thought theoretically.

The research results were published in the Proceedings of the National Academy of Sciences. Wallner suggested that future studies of older samples could help determine the fluctuations in iron-60 levels.