heic2511 \u2014 Science Release<\/p>\n
18 September 2025<\/p>\n
In our nearby stellar neighbourhood, a burned-out star is snacking on a fragment of a Pluto-like object. With its unique ultraviolet capability, only the NASA\/ESA Hubble Space Telescope could identify that this meal is taking place.<\/p>\n
The stellar remnant is a white dwarf about half the mass of our Sun, but that is densely packed into a body about the size of Earth. Scientists think the dwarf\u2019s immense gravity pulled in and tore apart an icy Pluto analogue from the system\u2019s own version of the Kuiper Belt, an icy ring of debris that encircles our Solar System. The findings were reported on 18 September 2025 in the Monthly Notices of the Royal Astronomical Society.<\/p>\n
An international team of astronomers were able to determine this carnage by analysing the chemical composition of the doomed object as its pieces fell onto the white dwarf. In particular, they detected \u201cvolatiles\u201d (substances with low boiling points) including carbon, sulphur, nitrogen, and a high oxygen content that suggests the strong presence of water.<\/p>\n
\u201cWe were surprised,\u201d said Snehalata Sahu of the University of Warwick in the United Kingdom. Sahu led the data analysis of a Hubble survey of white dwarfs. \u201cWe did not expect to find water or other icy content. This is because the comets and Kuiper Belt-like objects are thrown out of their planetary systems early, as their stars evolve into white dwarfs. But here, we are detecting this very volatile-rich material. This is surprising for astronomers studying white dwarfs as well as exoplanets, planets outside our Solar System.\u201d<\/p>\n
Only with Hubble<\/p>\n
Using Hubble\u2019s Cosmic Origins Spectrograph<\/a>, the team found that the fragments were composed of nearly two thirds water ice. The fact that they detected so much ice meant that the pieces were part of a very massive object that formed far out in the star system\u2019s icy Kuiper Belt analogue. Using Hubble data, scientists calculated that the object was bigger than typical comets and may be a fragment of an exo-Pluto.<\/p>\n They also detected a large fraction of nitrogen – the highest ever detected in white dwarf debris systems. \u201cWe know that Pluto’s surface is covered with nitrogen ices,\u201d said Sahu. \u201cWe think that the white dwarf accreted fragments of the crust and mantle of a dwarf planet.\u201d<\/p>\n Accretion of these volatile-rich objects by white dwarfs is very difficult to detect in visible light. These volatile elements can only be detected with Hubble\u2019s unique ultraviolet light sensitivity. In optical light, the white dwarf would appear ordinary.<\/p>\n About 260 light-years away, the white dwarf is a relatively close cosmic neighbor. In the past, when it was a Sun-like star, it would have been expected to host planets and an analogue to our Kuiper Belt.<\/p>\n Like seeing our Sun in the future<\/p>\n Billions of years from now, when our Sun burns out and collapses to a white dwarf, Kuiper Belt objects will be pulled in by the stellar remnant\u2019s immense gravity. \u201cThese planetesimals will then be disrupted and accreted,\u201d said Sahu. \u201cIf an alien observer looks into our Solar System in the far future, they might see the same kind of remains we see today around this white dwarf.\u201d<\/p>\n The team hopes to use the NASA\/ESA\/CSA James Webb Space Telescope<\/a> to detect molecular features of volatiles such as water vapour and carbonates by observing this white dwarf in infrared light. By further studying white dwarfs, scientists can better understand the frequency and composition of these volatile-rich accretion events.<\/p>\n