'Story is complicated': Discovery of rare radioactive plutonium isotope stuns scientists

Researchers have found traces of plutonium in ocean crust alongside radioactive iron as per a study published in the journal Science. The researchers have claimed that the two isotopes are evidence of "violent cosmic" events in the vicinity of Earth millions of years ago. The rare radioactive plutonium isotope dating back millions of years led experts to question how it originated on the Blue Planet. Physicist Anton Wallner from the Australian National University, who also holds joint positions at the Helmholtz-Zentrum Dresden-Rossendorf (HZDR) and Technical University Dresden in Germany conducted this work with researchers from Australia, Israel, Japan, Switzerland and Germany. 

'The story is complicated'

The element is known as plutonium-244 and was discovered nearly 5,000ft below the Pacific Ocean in the ocean crust. It is worth noting that star explosions or supernovae create many of the heavy elements in the periodic table, including those essential for human life, such as iron, potassium and iodine. However, in order to form even heavier elements, such as gold, uranium and plutonium — a more violent event may be required, such as two neutron stars merging. As per the findings, the element iron-60 was also discovered. 

"The story is complicated - possibly this plutonium-244 was produced in supernova explosions or it could be left over from a much older, but even more spectacular event such as a neutron star detonation," the study's lead author, The Australian National University Anton Wallner said.

The study explained that any plutonium-244 and iron-60 that existed when the Earth was formed from interstellar gas and dust over four billion years ago has long since decayed. However, the sample that has been discovered must have originated from recent cosmic events in space. The dating of the sample has confirmed that two or more supernova explosions occurred near earth. 

"Our data could be the first evidence that supernovae do indeed produce plutonium-244. Or perhaps it was already in the interstellar medium before the supernova went off, and it was pushed across the solar system together with the supernova ejecta," Professor Wallner said. 

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