Webb telescope finds water ice around distant star for the first time

Astronomers have been searching for water ice outside of our solar system for years. They expected to find it. They knew it existed on moons and dwarf planets around Jupiter, Saturn, and beyond. But they couldn’t confirm it around other stars. Until now.

The James Webb Space Telescope just changed everything. Researchers aimed its Near-Infrared Spectrograph (NIRSpec) at HD 181327, a Sun-like star 155 light-years away. What they found was crystalline water ice swirling in a dusty debris disk around the star.

Chen Xie is the lead author of the study and assistant research scientist at Johns Hopkins University.

“Webb unambiguously detected not just water ice, but crystalline water ice,” said Xie. “It’s also found in locations like Saturn’s rings and icy bodies in our solar system’s Kuiper Belt.”

Water ice around distant stars

Astronomers have long suspected water ice in these distant disks. Spitzer, a retired space telescope, hinted at it back in 2008. But its instruments weren’t sensitive enough to confirm it. That’s where Webb comes in.

Webb can detect the faintest traces of ice, dust, and rock. Its instruments can pick up on tiny particles that other telescopes miss. This level of precision allowed researchers to confirm the presence of crystalline water ice around HD 181327.

Xie emphasized the significance of the discovery. “The presence of water ice helps facilitate planet formation,” he said. “Icy materials may also ultimately be ‘delivered’ to terrestrial planets that may form over a couple hundred million years in systems like this.”

A chaotic debris disk

HD 181327 is young. Just 23 million years old. Compare that to our Sun, which is 4.6 billion years old. This star is hotter and more massive than the Sun, and its system is a mess. Dust, rock, and icy bodies collide and scatter, creating a chaotic debris disk.

Christine Chen, co-author and associate astronomer at the Space Telescope Science Institute, described the scene.

“HD 181327 is a very active system. There are regular, ongoing collisions in its debris disk. When those icy bodies collide, they release tiny particles of dusty water ice that are perfectly sized for Webb to detect,” noted Chen.

Webb detected a significant gap between the star and its debris disk. A wide, empty zone. This gap could indicate the presence of forming planets, sweeping up debris as they orbit. Beyond that gap, the disk resembles our Kuiper Belt – a region filled with icy bodies, comets, and dwarf planets.

Water ice everywhere – almost

Water ice isn’t spread evenly in the HD 181327 system. In the outer disk, where temperatures are colder, ice particles make up more than 20% of the material.

Move closer to the star, and the amount of ice drops to around 8%. Here, icy particles form faster than they break apart. But the inner disk? Almost no water ice – ultraviolet light from the star likely vaporizes it, or rocky planetesimals might be trapping it inside their cores.

“When I was a graduate student 25 years ago, my advisor told me there should be ice in debris disks,” said Chen. “But prior to Webb, we didn’t have instruments sensitive enough to make these observations.”

Water ice and planet formation

Icy bodies do more than drift through space. They collide, break apart, and scatter particles. These particles can clump together, forming the seeds of new planets. Over millions of years, icy debris could deliver water and other vital compounds to rocky worlds.

Researchers think this is how Earth got its water – icy comets and asteroids crashing into a young, molten planet. Now, they’re looking at HD 181327’s disk and asking the same questions.

Could icy bodies there deliver water to forming planets? And if so, could these planets develop habitable conditions?

Future research directions

Webb has only just begun its mission. It’s equipped to scan more debris disks around other stars, searching for signs of water ice. Each discovery adds a new piece to the puzzle of how icy bodies evolve and interact in young planetary systems.

NASA, ESA, and CSA built Webb to answer the big questions: How do stars and planets form? Where does water come from? And could icy bodies in distant systems deliver the same life-sustaining molecules that once fell to Earth?

For now, researchers are focused on HD 181327. They’re mapping the distribution of water ice, measuring its concentration, and tracking how it moves. Webb’s instruments are sensitive enough to detect the tiniest particles, revealing hidden dynamics in these faraway systems.

The presence of crystalline water ice around HD 181327 marks a turning point. For the first time, astronomers can study icy debris disks beyond our solar system with clarity and precision. And as they do, they’re not just looking for water. They’re looking for the building blocks of life itself.

The study is published in the journal Nature.

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