Scientists have long puzzled over how the heaviest elements on the periodic table—like uranium and plutonium—are formed.
Now, researchers led by Los Alamos National Laboratory have proposed a bold new idea: that stars collapsing into black holes can blast jets of energy that turn parts of the star into a flood of neutrons, allowing heavy elements to form.
Their study, published in The Astrophysical Journal, suggests that during a star’s collapse, extremely high-energy photons (particles of light) inside a powerful jet could strip apart atomic nuclei.
This would free up neutrons—the key ingredient needed to create heavy elements through a process called “rapid neutron capture,” or the r-process.
Normally, free neutrons don’t last long; they decay within about 15 minutes. So for the r-process to happen, there needs to be an enormous amount of neutrons created very quickly. This new idea suggests the neutrons are produced on the spot, rather than already existing in large numbers.
Here’s how it might work: As a massive star runs out of fuel, its core collapses into a black hole. If the black hole spins fast enough, it twists surrounding magnetic fields, launching a jet of high-energy material outward. As this jet pushes through the outer layers of the star, it creates a hot bubble, or cocoon, around it—similar to a freight train plowing through snow.
At the point where the jet meets the star’s material, high-energy photons slam into atomic nuclei, turning protons into neutrons. Some nuclei are even completely broken apart into free protons and neutrons. Because neutrons have no electric charge, they aren’t trapped by the magnetic fields like protons are. Instead, they escape into the surrounding cocoon.
Once there, these dense clouds of neutrons could kick off the r-process, forging new heavy elements. These elements would then be flung into space as the star is torn apart.
This idea connects many areas of physics—from atomic and nuclear reactions to general relativity—and could help explain several cosmic mysteries. For example, it may offer a new explanation for kilonovas, the bright flashes of light that follow some gamma-ray bursts. Until now, kilonovas were mostly linked to collisions between neutron stars. But this new model suggests that collapsing stars could also create them.
The theory might also help explain why scientists have found traces of heavy elements like iron and plutonium in deep-sea sediments on Earth, likely from cosmic events millions of years ago.
To test their ideas, the research team plans to run detailed computer simulations. Their work could bring us closer to understanding the powerful, chaotic environments where the universe’s heaviest elements are born.
Source: Los Alamos National Laboratory.
