A White Dwarf and an Ice-World Snack
Astronomers using the Hubble Space Telescope have identified a white dwarf star—an ultra-dense, compact stellar remnant—that appears to have consumed an icy body resembling Pluto. The finding, published in Monthly Notices of the Royal Astronomical Society, provides a striking clue about the kinds of frozen material that exist around other stars and what they might mean for habitable planets beyond the Solar System.
The white dwarf in question lies in the Milky Way, about 255 light-years from Earth, making it relatively nearby in cosmic terms. It has a mass roughly 0.57 times that of the Sun and, despite its Earth-sized diameter, packs about 190,000 times the mass of Earth into its compact form. This paradox—immense mass compressed into an Earth-sized sphere—illustrates why white dwarfs are among the universe’s most extreme objects.
How the team spotted the trace of an icy, Pluto-like body
Historically, white dwarfs are known to “eat”or accrete material from the bodies that orbit or once orbited them, including rocky planets, moons and asteroids. In this case, researchers detected an unusual chemical fingerprint on the atmosphere of the white dwarf using the Hubble Space Telescope’s Cosmic Origins Spectrograph, which analyzes ultraviolet light from distant objects. The data revealed an unusually high abundance of nitrogen—an ingredient common in Pluto-like ices—alongside other elements that mark the remnants of an icy world rather than a typical rocky asteroid or comet.
Lead author Snehalata Sahu, a postdoctoral researcher in astrophysics at the University of Warwick, explained that the signal strongly suggests fragments from the surface and mantle of an icy world gushed toward the white dwarf and were subsequently torn apart by its intense gravity. Fellow Warwick astrophysicist Boris Gaensicke notes that, once drawn within a distance comparable to the Sun’s own width, the body would be distorted, fractured and ultimately accreted onto the star.
Why nitrogen matters—and what this means for exoplanet science
“The key evidence comes from an unusually high nitrogen abundance, which is more consistent with ice-rich material than with typical cometary debris found around other white dwarfs,” Sahu said. The detection would not be possible without ultraviolet spectroscopy, which highlights the spectral fingerprints of elements in the star’s atmosphere as it absorbs material from the infalling debris.
In the broader context, the team’s work reinforces a growing view that planets and their icy constituents—common in the outer regions of planetary systems—exist far beyond our solar neighborhood. Pluto-like bodies, or similar volatile-rich worlds, may be more common than previously thought. The presence of such icy material in other systems has important implications for the delivery of water and volatiles to rocky planets, a process considered critical to the emergence of life as we know it on Earth and perhaps elsewhere.
Implications for habitability beyond the Solar System
The study’s authors argue that detecting water-rich and nitrogen-bearing ices around other stars strengthens the idea that reservoirs of icy material exist throughout the galaxy. If Pluto-like bodies are common, they could play a comparable role in supplying water and organics to rocky exoplanets, thereby increasing the odds that some worlds become habitable. While the white dwarf’s feast occurred in a distant system, the observation provides a tangible link between cold, icy bodies and the chemical ingredients scientists associate with prebiotic chemistry and potential life-supporting environments.
Looking ahead
As telescopes and spectrographs continue to refine their sensitivity, astronomers expect more discoveries of this kind—cases where white dwarfs reveal the rocky and icy remnants of planetary systems that survived long after their stars have left the main sequence. Such findings help scientists map the distribution of water-bearing bodies across the galaxy and deepen our understanding of where habitable environments might arise outside the Solar System.
