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| For the first time, scientists have confirmed crystalline water ice in a dusty debris disk around a Sun-like star, thanks to NASA’s James Webb Space Telescope — with most ice found in the cold, outer regions, and little to none near the star. |
Definitive evidence of frozen water — or crystalline water ice — has been discovered in a star system 155 light-years from Earth, offering new insight into how planetary systems form.
For decades, astronomers suspected that frozen water exists in star systems beyond our own, based on indirect evidence like water vapor and the presence of ice in our solar system. Now, NASA’s James Webb Space Telescope (JWST) has provided the clearest proof yet: water ice embedded in a dusty debris disk orbiting a young Sun-like star.
Researchers used Webb’s powerful spectroscopic instruments to detect not just water ice, but crystalline water ice — the same kind found in Saturn’s rings and the Kuiper Belt, a cold, distant region beyond Neptune where icy bodies and comets reside.
“Webb unambiguously detected not just water ice, but crystalline water ice,” said Chen Xie, lead author of the study and a research scientist at Johns Hopkins University. The findings were published Wednesday in the journal Nature.
A Cold and Chaotic Disk.
The star, known as HD 181327, is only about 23 million years old — much younger than our 4.6-billion-year-old Sun — and slightly more massive and hotter. Around it swirls a dusty ring of debris, shaped similarly to our own Kuiper Belt.
Webb’s data reveals a large dust-free gap between the star and its outer disk, suggesting dynamic activity. Beyond that gap, tiny particles of dust and ice — likened to “dirty snowballs” — collide and churn, producing just the right conditions for JWST to detect their composition.
“This system is very active,” said co-author Christine Chen of the Space Telescope Science Institute. “There are ongoing collisions in the debris disk, and when icy bodies collide, they release fine particles of dusty water ice.”
Water Ice: A Planetary Building Block.
Water ice plays a critical role in shaping planetary systems. It not only contributes to the formation of gas giants but may also be delivered to rocky worlds, like Earth, via comets and asteroids.
Webb’s observations show that the amount of water ice varies across the disk. The cold outer regions contain over 20% water ice, while the middle zone shows about 8%. Closer to the star, almost no water ice is found — likely vaporized by the star’s intense ultraviolet light or locked inside rocky planetesimals.
“This discovery opens the door to studying how water and other ices help planets form,” said Xie. “It also shows how icy materials might be delivered to young, rocky planets in systems like this one.”
A Milestone in Space Exploration.
The discovery fulfills a long-standing goal in astronomy. “When I was a graduate student 25 years ago, my advisor told me there should be ice in debris disks,” Chen said. “But before Webb, we didn’t have the instruments to detect it.”
Using Webb’s Near-Infrared Spectrograph (NIRSpec), researchers were able to detect extremely faint signals from fine dust grains in deep space — something impossible with ground-based telescopes or earlier missions like NASA’s Spitzer Space Telescope, which hinted at the presence of ice back in 2008.
Now, scientists will use Webb to continue hunting for frozen water in other planetary nurseries throughout the galaxy — a quest that may ultimately help us understand the origins of habitable worlds.
The James Webb Space Telescope is a joint mission of NASA, the European Space Agency (ESA), and the Canadian Space Agency (CSA). It remains the most advanced space observatory ever built, capable of peering into the earliest chapters of the universe and unlocking secrets far beyond our solar system.