We may have found the source of some the universe’s heaviest elements.
In March, astronomers using the James Webb Space Telescope observed two runaway neutron stars collide in a staggering explosion that discharged a gamma ray burst (GRB) over one million times brighter than the entire Milky Way galaxy — the second brightest of its kind ever observed.
Now, in a new study published in the journal Nature, the astronomers confirm that the intense forces in the explosion, known as a kilonova, fused rare heavy metals like tellurium in the event's aftermath. It may be the strongest proof yet that GRBs caused by explosions like a kilonova play a central role in the creation of these heavy elements across the universe.
"For the first time we have evidence of these particular kinds of elements being formed in these mergers," study lead author Andrew Levan, an astrophysicist at Radboud University in the Netherlands, told The Guardian.
"It's 150 years since we've had the [periodic table] and we still don't know where a good number of elements come from," he added. "One of the things we're trying to do is fill in those gaps."
Neutron stars are the collapsed cores of massive stars, and are considered to be some the densest objects in the cosmos. Think of them as a star as big or several times bigger than our Sun crushed into the size of a city.
The two stars observed in the study were part of a binary system that was ejected 120,000 light years away from their home galaxy, the researchers said, spending billions of years gradually spiraling closer together.
The resulting explosion was extraordinary in more ways than one. The GRB was not only remarkably bright, but unusually long as well, lasting 200 seconds. That's far longer than most previously identified GRBs caused by merging neutron stars, which only last less than two seconds, though only a handful have ever been observed.
Despite the rarity of kilonovae, the detection of tellurium suggests that other heavy elements nearby on the periodic table like iodine — considered to be essential to sustaining life on Earth — as well as thorium, are spread throughout the cosmos by these epic explosions. Lighter elements like iron, by contrast, are believed to be fused in the cores of stars.
"About half of the elements heavier than iron are probably made in these events," Levan told The Guardian. "We hoped to see this, but you never quite know what you're going to get."
But the researchers studying these immense explosions are only getting started. Ideally, they hope to catch more of these GRBs in the act.
"Our next job is to find more of these long-lived mergers and develop a better understanding of what drives them — and whether even heavier elements are being created," said co-author Ben Gompertz, an astronomer at the University of Birmingham, said in a statement about the work.
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