— Using the James Webb Space Telescope, the XUE collaboration has identified an atypical protoplanetary disk around the young star XUE 10 in NGC 6357, about 5,550 light-years away; the disk shows unusually high carbon dioxide and very low water in the planet-forming zone, a composition that challenges standard models of disk chemistry and evolution.
Key Takeaways
- JWST observations of XUE 10 reveal a protoplanetary disk unusually enriched in carbon dioxide (CO2) in its inner, planet-forming region.
- The disk shows a marked scarcity of water vapor where water is normally prominent in similar nearby disks.
- Detected CO2 carries heavy isotopes: carbon-13 and oxygen-17 and oxygen-18 were reported.
- The system lies in the massive star-forming complex NGC 6357, roughly 5,550 light-years from Earth.
- Researchers suggest intense ultraviolet radiation — from the host or neighboring massive stars — may be reshaping the disk’s chemistry.
- Findings were reported by the XUE collaboration and published in Astronomy & Astrophysics on Aug. 29, 2025.
- The result has implications for how planetary atmospheres and volatile inventories develop in harsh stellar environments.
Verified Facts
The target, designated XUE 10, resides in NGC 6357, a well-known, massive star-forming region. JWST spectroscopy detected strong signatures of carbon dioxide concentrated in the inner regions of the surrounding protoplanetary disk, where rocky planets are expected to assemble. At the same time, water vapor signals in that zone are much weaker than commonly observed in nearby, less extreme disks.
Researchers from the eXtreme Ultraviolet Environments (XUE) collaboration analyzed the JWST data and reported the unusually high CO2-to-water ratio. Team members noted that the CO2 shows enrichment in the isotopes carbon-13 and oxygen-17 and oxygen-18, measurements that may help explain isotopic anomalies preserved in solar system materials such as meteorites and comets.
The paper was released on Aug. 29, 2025, in the journal Astronomy & Astrophysics. The investigation emphasizes environments with strong ultraviolet radiation, which can alter molecular abundances by dissociating molecules and driving chemical pathways that differ from those in calmer disks.
Context & Impact
Standard models of inner-disk chemistry rely on pebble drift: icy grains from the cold outer disk migrate inward, sublimate, and enrich inner regions with water vapor. The XUE 10 disk departs from this picture, suggesting that either inward transport behaved differently here or subsequent processing removed or transformed water into other species such as CO2.
Massive star-forming regions like NGC 6357 expose young disks to elevated ultraviolet fields and winds from nearby O- and B-type stars. If such radiation commonly drives chemistry toward CO2-rich, water-poor compositions, planets forming in these neighborhoods could inherit very different volatile budgets and atmospheric starting points than planets formed in quieter regions.
Practical implications include a wider diversity of planetary atmospheres and potential impacts on habitability assessments. The discovery underlines the need to survey more disks across varied environments to determine how common these chemically altered disks are.
- Potential impacts: altered volatile delivery, changed atmospheric compositions, different organics chemistry.
- Next steps: targeted JWST spectroscopy of other disks in high-UV regions and complementary ALMA observations to map solids and ices.
“Unlike most nearby planet-forming disks, where water vapor dominates the inner regions, this disk is surprisingly rich in carbon dioxide,”
Jenny Frediani, XUE collaboration / Stockholm University
Unconfirmed
- Whether the CO2 enrichment is caused primarily by ultraviolet radiation from XUE 10 itself or by nearby massive stars remains unresolved.
- It is not yet known if planets will actually form in this particular disk or whether forming bodies will retain or lose volatiles like water.
- The prevalence of CO2-dominated inner disks across other massive star-forming regions requires further survey data.
Bottom Line
JWST has revealed a planet-forming disk whose chemistry departs from textbook expectations: inner zones rich in CO2 and poor in water. This finding suggests environmental radiation can substantially rework the building blocks of planets, and it pushes astronomers to broaden observations and models to include more extreme stellar nurseries.