Webb Discovers Crystallized Water Ice in Debris Disks Surrounding Young Sun-Like Stars

Water ice plays a crucial role in the formation of giant planets and can also be delivered by comets to fully developed rocky planets. Utilizing data from the Near-infrared spectrometer (NIRSPEC), which is part of the NASA/ESA/CSA James Webb Space Telescope, astronomers have identified crystallized ice on a dusty fragment disk surrounding HD 181327.

HD 181327 is a young main sequence star located approximately 169 light years away in the constellation Pictor.

Also referred to as TYC 8765-638-1 and WISE J192258.97-543217.8, the star is about 23 million years old and roughly 30% larger than the Sun.

Astronomer Chen Zai and a team at Johns Hopkins University utilized Webb’s NIRSPEC instrument to study HD 181327.

“The HD 181327 system is highly dynamic,” Dr. Xie noted.

“There are ongoing collisions occurring within the debris disk.”

“When these icy bodies collide, they release tiny particles of dusty water ice, which are ideally sized for Webb to detect.”

Webb’s observations reveal a significant gap between the star and its surrounding debris disk, indicating a considerable area devoid of dust.

Moreover, the structure of the fragment disk is reminiscent of the Kuiper Belt within our Solar System, where we find dwarf planets, comets, and various icy and rocky bodies that may also collide.

Billions of years ago, the Kuiper Belt in our own Solar System could have resembled the HD 181327 debris disk.

“Webb clearly detected crystallized water ice not only present in the debris disk but also in places like Saturn’s rings and the icy bodies of the Kuiper Belt,” Dr. Xie stated.

The water ice is not uniformly distributed across the HD 181327 system.

The majority is found in the coldest and most distant regions from the star.

“The area beyond the debris disk contains over 20% water ice,” Dr. Xie explained.

Near the center of the debris disk, Webb detected approximately 8% water ice.

In this region, frozen water particles may form slightly faster than they are destroyed.

Closest to the star, Webb’s detection was minimal.

Ultraviolet radiation from the star can evaporate the nearby water ice deposits.

It is also possible that the interiors contain rocky bodies, referred to as planets, which are “confined” such that their frozen water remains undetectable by Webb.

“The presence of ice facilitates planetary formation,” said Dr. Xie.

“Icy materials can ultimately contribute to the delivery of resources to terrestrial planets that may form over hundreds of millions of years in such systems.”

Survey results were published in the May 14, 2025 issue of the journal Nature.

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C. Xie et al. 2025. Water ice on debris disks around HD181327. Nature 641, 608-611; doi:10.1038/s41586-025-08920-4