New finding from Hubble reveals a white dwarf feasting on an icy Pluto-like world
Astronomers using the Hubble Space Telescope have identified a striking example of a white dwarf—one of the universe’s most compact stellar remnants—appearing to have consumed an icy, Pluto-like body. The star resides in the Milky Way, roughly 255 light-years from Earth, and has a mass about 0.57 times that of the Sun. While white dwarfs are sealed within Earth-sized volumes, their intense gravity can rip apart and accrete orbiting bodies, and this recent observation provides a rare window into those processes.
How the discovery was made
The key evidence comes from the chemical fingerprints observed in the white dwarf’s atmosphere. Using the Cosmic Origins Spectrograph on Hubble, researchers measured ultraviolet light emitted by the star and detected unusually high levels of nitrogen. Such a chemical pattern is hard to reconcile with typical rocky material, and it points to the ingestion of an icy body rich in nitrogen—similar in composition to the outer solar system’s Pluto or similar icy worlds. The team concluded that the white dwarf’s strong gravity has broken apart a Pluto-like object, with fragments spiraling inward and gradually being accreted onto the stellar remnant.
In describing the discovery, lead author Snehalata Sahu, a postdoctoral researcher at the University of Warwick, explained that the observed material likely originated from the crust and mantle of an icy world rather than a purely rocky body. Co-author Boris Gaensicke noted that as such a body approached the white dwarf, tidal forces would distort it until it fractured and disintegrated, feeding the star’s surface with debris.
What this means for ice and water beyond our Solar System
The finding demonstrates that Pluto-like, ice-rich bodies exist around other stars and can survive long enough to interact with the remnant white dwarfs that remain after their suns have faded. Sahu highlighted that the abundance of nitrogen observed aligns with surfaces dominated by nitrogen-rich ices, a hallmark of Pluto-like worlds. Gaensicke emphasized that the phenomenon is not a rare curiosity but a natural outcome in many evolved planetary systems, where icy bodies orbit stars and can eventually be drawn into the white dwarf’s gravity well.
The study also reinforces a broader astronomical principle: the presence of water-bearing or volatile-rich bodies in other planetary systems. In our own solar system, comets and icy planetesimals delivered water and other volatiles to the inner planets, potentially shaping habitability. If Pluto-like objects are common in other systems, they may similarly contribute essential ingredients for life-bearing environments elsewhere, even as their parent stars transition into white dwarfs.
Implications for the search for life beyond the Solar System
While a white dwarf is not a traditional host for life as we know it, understanding the distribution of icy bodies across the galaxy helps astronomers map where water, carbon, and other volatiles reside. The observed nitrogen signature adds a concrete data point: icy worlds exist in distant planetary systems and can be detected indirectly through a white dwarf’s polluted atmosphere. This expands our picture of planetary system architecture and the kinds of worlds that may harbor the raw materials for habitability, long after a star’s main-sequence life has ended.
Broader significance
Ultimately, the discovery underscores a key theme in modern astronomy: planetary formation and evolution appear to follow common threads across the cosmos. By studying how white dwarfs accumulate material from shattered icy bodies, scientists gain insight into the prevalence of Pluto-like worlds and the distribution of water-rich material in the galaxy. These observations keep pointing toward a universe where habitable ingredients are widespread, even if the contexts differ greatly from our own planetary neighborhood.
