Scientists claim that they are able to analyze material from the sea bed to improve our understanding of cosmic supernovae.
Researchers from the Research School of Physics and Engineering at the Australian National University say that the dust was once part of exploding stars far outside our solar system, before it traveled through space and came to rest on Earth.
“Small amounts of debris from these distant explosions fall on the earth as it travels through the galaxy,” said lead researcher Anton Wallner.
Looking for heavy elements
The undersea dust contains different amounts of heavy elements, believed to be created by cosmic explosions, than current supernova theory suggests.
“We’ve analyzed galactic dust from the last 25 million years that has settled on the ocean and found there is much less of the heavy elements such as plutonium and uranium than we expected,” Wallner says.
Scientists currently believe that supernovae create the building blocks of human life, including iron, iodine and potassium, and cause them to move across space. The explosions also create heavy elements uranium and plutonium, as well as gold, silver and lead.
Space dust under sea
During the study the scientists took samples from the sea bed which represented 25 million years of sediment accretion, before analyzing them. They were looking for plutonium-244 in particular, because we know it has a half-life of 81 million years, and this information allows scientists to accurately gauge the age of a sample.
Plutonium produced by the formation of the Earth would have decayed long ago, which means that “any plutonium-244 that we find on earth must have been created in explosive events that have occurred more recently, in the last few hundred million years,” Wallner says.
However levels of the radioactive element were found to be “100 times less” than expected.
The results have thrown current astrophysical theory into doubt and suggest that the heaviest elements in a supernova form in a different way than previously thought, because we know that supernovas have been exploding in the vicinity of Earth, but levels of heavy elements are lower than current models predict.
Wallner claims that standard supernovae may not be enough to form these heavy elements, whose formation may require “more explosive events such as the merging of two neutron stars.”