JWST reveals a planet-forming disk in NGC 6357 with unusually high carbon dioxide and scarce water vapor, challenging current models of planet formation (Photo: Freepik)
Astronomers studying young planetary systems have been astonished by something out of an oddity. A planet forming disk with an unusual amount of carbon dioxide (CO2) has been identified by an international team of researchers led by Jenny Frediani at Stockholm University.
Reported in Astronomy & Astrophysics, this discovery made possible by the James Webb Space Telescope (JWST) challenges established theories regarding how planets are formed.
The vapor of water defines this warm inner region of such disks. As icy pebbles move in from these colder zones and the heat of the disk usually converts this water ice into vapor and hence leaving a strong signature in observations.
However, the MIRI instrument of JWST has shown that water is almost absent or very close to being undetectable, while CO2 is dominating the chemical architecture. According to Frediani, such a chemical composition defies conventional models and indicates an unexpected evolutionary path for this system.
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The researchers posit that this anomaly might be related to intense ultraviolet radiation, either from the central star itself or from nearby massive stars in the region. Such radiation might disrupt the equilibrium between water and its constituents, eventually breaking down water and thereby enriching carbon dioxide.
This accumulation of CO2 cannot be explained by normal disk dynamics, according to Arjan Bik of Stockholm University. The external influence stands out as the most likely driving factor for the changes.
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CO2, the team has enriched isotopic variants containing carbon 13 and oxygen isotopes like 17O and 18O. These could help solve long-standing questions concerning the isotopic signatures observed in comets and meteorites from the early solar system. The disk itself is embedded in the NGC 6357 stellar nursery, some 5,500 light years away.
This observation is a part of the eXtreme Ultraviolet Environments (XUE) project pursuing investigations into how high energy radiation affects disk chemistry and hence planetary formation. Such research is critical to explain why planetary systems are so different and what that implies for their ability to sustain life, according to project leader Maria Claudia Ramirez Tannus.
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