In a new study, led by Jenny Frediani of the Department of Astronomy at Stockholm University, researchers have discovered a planet-forming disk. This disk has an unexpected chemical composition to say the least. We see this disk in the massive star-forming region numbered NGC 6357. To everyone’s surprise, it revealed that there is an unexpectedly high abundance of carbon dioxide (CO₂) where Earth-like planets could one day form. The study, which calls into question prevailing models of planet formation, was published in the journal Astronomy & Astrophysics.
The thick disk was discovered about 1.7 kiloparsecs, or about 53 trillion kilometers, from Earth. Utilizing the capabilities of the James Webb Space Telescope’s Mid-Infrared Instrument (JWST/MIRI), researchers detected four distinct forms of carbon dioxide within the disk’s spectrum. Water was perhaps the biggest surprise in the planet-forming disks examined. This discovery begs the question of what conditions, if any, are needed to form planets in these markedly different environments.
Frediani emphasized the significance of their findings, stating, “Unlike most nearby planet-forming disks, where water vapor dominates the inner regions, this disk is surprisingly rich in carbon dioxide.” She mentioned how water is incredibly limited in this system. This renders it almost undetectable, developing a shocking counterpoint to what we typically observe.
The ramifications of this find stretch well beyond the science of chemistry. According to Arjan Bik, a researcher at Stockholm University, “Such a high abundance of carbon dioxide in the planet-forming zone is unexpected. It points to the possibility that intense ultraviolet radiation—either from the host star or neighboring massive stars—is reshaping the chemistry of the disk.”
Maria-Claudia Ramirez-Tannus, leader of XUE collaboration, noted the general relevance of their findings. It further uncovers how extreme radiation environments—typical of massive star-forming regions—are capable of transforming the complex building blocks of planets. So even today, most stars and planets form in highly confined areas. Thus, elucidating these effects is key to understanding the complexity of planetary atmospheres and their extreme diversity in terms of habitability.
The widespread detection of high levels of CO₂ compared to H2O poses a challenge to our understanding of disk chemistry and evolution. Frediani stated, “This challenges current models of disk chemistry and evolution since the high carbon dioxide levels relative to water cannot be easily explained by standard disk evolution processes.”
This surprising finding opens up thrilling new avenues of research into the chemical environment in which planets are born. Lastly, it encourages curiosity in investigating how varying circumstances shape planetary evolution. Scientists are ready to explore distant star-forming regions. They hope to understand the circumstances that ignite planet formation and expose the possibilities of life elsewhere in the universe.