Scientists have discovered the first indications that nuclear fission is taking place between stars. The discovery supports the idea that when neutron stars collide, they create 'superheavy' elements - heavier than the heaviest elements on the periodic table - which are then broken down via nuclear fission to birth elements such as the gold in your jewelry.
Nuclear fission is actually the opposite of nuclear fusion. While nuclear fusion refers to destroying lighter elements to create heavier elements, nuclear fission is a process in which energy is released when heavy elements break apart to create lighter elements. Nuclear fission is also quite well known. It is actually the base of the energy-generating nuclear power plants here Soil - however, it was not seen among the stars for now.
"People have thought fission was happening in the cosmos, but so far no one has been able to prove it," said Matthew Mumpower, co-author of the study and a scientist at Los Alamos National Laboratory. said in a statement.
The team of researchers led by scientist Ian Roederer of North Carolina State University sifted through data on a wide range of elements in stars to discover the first evidence that nuclear fission could therefore occur when neutron stars merge. These findings may help solve the mystery of where the universe where the heavy elements come from.
Related: What happens when neutron stars collide? Astronomers may finally knowScientists know that nuclear fusion is not only the main source of energy for stars, but also the force that forges a variety of elements, the "heaviest" of which is iron.
However, the picture of so-called nucleosynthesis for heavier elements such as gold and uranium was a little more mysterious. Scientists suspect that these valuable and rare heavy elements are created when two incredibly dense dead stars form: neutron stars - collide and merge, creating an environment violent enough to forge elements that even the most turbulent hearts of stars cannot create.
The evidence of nuclear fission discovered by Mumpower and team comes in the form of a correlation between 'light precision metals', such as silver, and 'rare earth nuclei', such as europium, which is visible in some stars. When one of these groups of elements increases, the corresponding elements in the other group also increase, the scientists saw.
The team's research also shows that elements with an atomic mass count for a number protons And neutrons in an atomic nucleus - more than 260 can occur around neutron star impacts, even if this existence is short-lived. This is much heavier than many of the elements on the "heavy side" of the periodic table.
"The only plausible way this can happen across different stars is if there is a consistent process occurring during the formation of the heavy elements," Mumpower said. "This is incredibly profound and is the first evidence of nuclear fission in the cosmos, confirming a theory we proposed several years ago."
"As we've made more observations, the cosmos is saying, 'Hey, there's a signature here, and it can only come from nuclear fission.'"
Neutron stars and nuclear fission
Neutron stars form when massive stars reach the end of their fuel supplies needed for intrinsic nuclear fusion processes, meaning the energy that sustained them against the inner pressures of their own stars has been used up. gravity stops. As the outer layers of these dying stars are blown away, star nuclei with masses between one and twice that of the sun collapses to a width of about 12 miles (20 kilometers).
This core collapse is happening so quickly that electrons and protons are compressed, creating a sea of neutrons so dense that just a tablespoon of this neutron star "stuff" would weigh more than 1 billion tons if brought to Earth.
When these extreme stars appear in a double pair, they orbit each other. And as they orbit each other, they lose their angular momentum as they send out elusive ripples in spacetime gravitational waves. This causes neutron stars to eventually collide, merge and, given their extreme and exotic nature, unsurprisingly create a very violent environment.
This ultimate merger of neutron stars releases a wealth of free neutrons, which are particles normally bound to protons in atomic nuclei. This allows other atomic nuclei in these environments to quickly grab these free neutrons - a process called fast neutron capture or the 'r-process'. This can cause the atomic nuclei to become heavier, creating superheavy elements that are unstable. These superheavy elements can then be split and broken down into lighter, stable elements such as gold.
In 2020, Mumpower predicted how the "fission fragments" of nuclei created by the r-process would be distributed. After this, Mumpower's collaborator and TRIUMF scientist Nicole Vassh calculated how the r-process would lead to the co-production of light precision metals such as ruthenium, rhodium, palladium and silver - as well as rare earth nuclei, such as europium, gadolinium and dysprosium. and holmium.
This prediction can be tested not only by looking at neutron star mergers, but also by looking at the abundance of elements in stars enriched by r-process created material.
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This new study looked at 42 stars and found the precise correlation predicted by Vassh. This showed a clear signature of the fission and decay of elements that are heavier than those found in the periodic table. This further confirms that neutron star collisions are indeed the locations where elements are heavier than those in the periodic table. iron is forged.
'The correlation is very robust for stars with r-process improvement for which we have sufficient data time nature produces one atom of silver it also produces comparatively heavier rare earth nuclei. The composition of these element groups is coordinated," Mumpower concluded. "We've shown that only one mechanism could be responsible: nuclear fission, and people have been racking their brains about this since the 1950s."
The team's research was published in the December 6 edition of the journal Science.
