Astronomers using NASA’s Hubble Space Telescope have witnessed a rare cosmic meal: a white dwarf star consuming pieces of a frozen world similar to Pluto.
Located just 260 light-years away, the star is a faint remnant of what was once a sun-like star.
Though only about the size of Earth, it packs half the mass of our Sun into its tiny body, creating an intense gravitational pull strong enough to tear apart nearby objects.
The victim in this case was a large icy fragment, likely once part of a dwarf planet that formed in the star’s version of a Kuiper Belt—the distant ring of icy debris that surrounds our own solar system.
As this chunk spiraled into the white dwarf, Hubble’s ultraviolet instruments detected the chemical fingerprints of its destruction.
To the team’s surprise, the fragments contained high levels of volatile substances, including carbon, sulfur, nitrogen, and especially oxygen, which pointed to an abundance of water.
“We did not expect to find this much water or other ices,” explained Snehalata Sahu of the University of Warwick, who led the analysis.
“Normally, icy objects are ejected from their systems when stars evolve into white dwarfs. Yet here we are detecting volatile-rich material being consumed.”
Using Hubble’s Cosmic Origins Spectrograph, the researchers determined that the fragments were made up of about 64 percent water ice.
This amount suggests that the object was far larger than an ordinary comet and may have been a broken piece of an “exo-Pluto.”
In addition, the debris contained more nitrogen than has ever been measured in a white dwarf system.
Since Pluto’s surface today is covered with nitrogen ice, scientists believe the destroyed object may have been a dwarf planet with a crust and mantle similar to Pluto’s.
Such volatile elements are invisible to telescopes that only see optical light, which is why Hubble’s ultraviolet vision was crucial. Without it, the white dwarf would have appeared like any other faint star.
The discovery also offers a glimpse of our solar system’s future. Billions of years from now, our Sun will burn through its fuel, shrink into a white dwarf, and begin pulling in outer solar system bodies such as Kuiper Belt objects.
“If an alien civilization observed us then, they might see the same thing happening to our planets and icy worlds,” Sahu noted.
The research team now hopes to use the James Webb Space Telescope to study the white dwarf in infrared light, which could reveal even more about the chemistry of these destroyed objects.
By piecing together such clues, astronomers are learning not only how planets form but also how water—an essential ingredient for life—finds its way to rocky worlds like Earth.
