Astronomers have discovered a surprising new source of some of the rarest and most valuable elements in the universe—massive flares from supermagnetized stars called magnetars.
These powerful explosions, lasting just seconds, may be responsible for producing up to 10% of the gold, platinum, and other heavy elements in our galaxy.
This discovery also solves a mystery that began in 2004, when a bright flash of light was detected by a space telescope.
The flash came from a magnetar, a type of neutron star with magnetic fields trillions of times stronger than Earth’s.
The initial burst was powerful enough to release more energy in a few seconds than our sun produces in a million years.
But what puzzled scientists at the time was a second, smaller signal that appeared ten minutes later. No one could explain it—until now.
A team of astronomers at the Flatiron Institute in New York has now figured out what happened. They say that second signal came from the birth of heavy elements, including gold and platinum.
Their research shows that the flare produced around a third of Earth’s mass in these heavy metals.
The findings were published in The Astrophysical Journal Letters.
This is only the second time scientists have directly confirmed how these elements are made. The first time was in 2017, when astronomers observed two neutron stars crashing into each other.
That kind of collision creates the extreme environment needed for a process called “rapid neutron capture,” or the r-process, which is how heavy elements form. However, such collisions are rare and can’t explain all the gold and platinum we find in the universe.
That’s where magnetars come in. These ultra-magnetic neutron stars can unleash giant flares that throw material from their crust into space. This material contains lots of neutrons—exactly what’s needed for the r-process to take place. As radioactive elements decay, they produce a glow and slowly turn into stable elements like gold.
In 2024, the team predicted that this glow would appear as a burst of gamma rays, a very energetic form of light. When they looked back at past gamma-ray observations, they realized that the 2004 event perfectly matched their predictions. The flare may have created around 2 million billion billion kilograms of heavy elements—roughly the mass of Mars.
Based on this, the researchers estimate that magnetar flares could be behind up to 10% of all the r-process elements in the Milky Way. The rest likely comes from neutron star mergers. But with so few events recorded, the full story is still unfolding. There could be other unknown sources of these elements as well.
Magnetar flares are especially exciting because they can happen very early in a galaxy’s life, helping explain why some young galaxies already have lots of heavy elements. Upcoming telescopes like NASA’s Compton Spectrometer and Imager, launching in 2027, will help scientists catch more of these rare flares.
To confirm an event, researchers will need to point ultraviolet telescopes at the flare’s location within minutes of a gamma-ray burst. It’s a high-speed race—but one that might reveal the true origins of the universe’s precious metals.
Source: Simons Foundation.
