In about 5 billion years, our Sun will run out of hydrogen fuel and collapse into a dense, Earth-sized remnant called a white dwarf.
Though it will no longer shine as it once did, this stellar core will still have strong gravity.
What happens to the planets around such a dead star has long intrigued scientists — and a recent discovery is offering surprising new clues.
Astronomers have found that a white dwarf about 145 light-years away, named LSPM J0207+3331, is still feeding on leftover pieces of its old planetary system.
This is remarkable because the star is nearly 3 billion years old — far older than most white dwarfs known to be consuming planetary debris.
The discovery shows that planetary systems can remain active and unstable long after their parent stars die.
The finding came from detailed observations made with the W. M. Keck Observatory in Hawaiʻi.
When astronomers analyzed the light from the white dwarf, they detected 13 different chemical elements in its atmosphere — a clear sign that rocky material had fallen onto the star. These elements, such as magnesium, silicon, and iron, match the composition of asteroids or small planets.
Researchers believe that sometime within the past few million years, a gravitational disturbance knocked one of these rocky bodies out of its orbit and sent it spiraling toward the white dwarf.
As it approached, the intense gravity tore it apart, creating a cloud of dust and debris that the star then began to absorb.
“The amount of rocky material is unusually high for a white dwarf of this age,” said astrophysicist Patrick Dufour from the Université de Montréal, one of the study’s authors.
Normally, the hydrogen-rich atmospheres of white dwarfs hide such chemical traces, so detecting them in this system is particularly exciting.
“Something clearly disturbed this system long after the star’s death,” said John Debes from the Space Telescope Science Institute. “Even after billions of years, there’s still material left that can pollute the white dwarf.”
This case supports the idea of delayed planetary instability — a process in which the orbits of surviving planets gradually become unstable over billions of years.
As these orbits shift, asteroids or smaller worlds can be thrown inward toward the dead star.
Astronomers are now searching for clues about what caused the disruption. It’s possible that a distant Jupiter-sized planet remains in the system and continues to influence smaller objects through its gravity.
The Gaia space telescope and NASA’s James Webb Space Telescope may soon help detect such planets or reveal whether a passing star triggered the chaos.
The study, published in The Astrophysical Journal Letters, suggests that even long after their fiery deaths, stars can keep reshaping their cosmic neighborhoods — and that planetary destruction is sometimes a very slow process indeed.
