“The atmosphere of an exoplanet 65 light-years away smells like rotten eggs.”

US Research Team “First Discovery of Hydrogen Sulfide in Exoplanet Atmosphere… Clue to Planetary Formation Environment”

‘(Seoul=Yonhap News) Reporter Lee Ju-young = It was revealed that hydrogen sulfide (H₂S), a malodor component produced when eggs rot, exists in the atmosphere of the gas giant exoplanet similar in size to Jupiter (HD 189733b) discovered in the constellation Vulpecula 65 light-years away from Earth in 2005.’

Artistic rendering of the Jupiter-sized exoplanet ‘HD 189733b’ 65 light-years away
[Provided by Roberto Molar Candanosa/Johns Hopkins University. Redistribution and DB prohibited]

‘The research team led by Professor Guangwei Fu at Johns Hopkins University in the United States announced on the 9th that they have discovered hydrogen sulfide in the atmosphere of the exoplanet HD 189733b, along with water (H₂O), carbon dioxide (CO₂), and carbon monoxide (CO), through the analysis of observation data from the James Webb Space Telescope (JWST) published in the scientific journal Nature.’

‘Professor Fu stated, “Sulfur is an important element in producing more complex molecules along with carbon, nitrogen, and oxygen, and further research is needed to understand planetary formation and composition materials,” and he added, “This discovery will serve as a stepping stone to discovering other exoplanets and understanding the formation processes of those planets.”‘

‘HD 189733b is one of the closest and hottest gas giants to Earth among exoplanets observed through the phenomenon of transiting, passing in front of a central star, with a distance from the central star only 1/13 that of the Sun-Mercury and an orbital period of only 53 hours.’

‘Although the harsh environment of 927°C makes the existence of life forms unlikely, it has attracted attention as a subject for studying the atmospheres of exoplanets because it has a confirmed atmosphere.’

‘In previous studies, molecules containing carbon and oxygen, such as water and carbon monoxide, were discovered in the atmosphere of HD 189733b, and claims were made about the existence of carbon dioxide and methane (CH₄), but these were not confirmed.’

‘The research team observed HD 189733b passing in front of the central star on August 25 and 29, 2022, using the Near Infrared Camera (NIRCam) mounted on the JWST. By analyzing the light passing through the atmospheric portion of the planet as it transits in front of the central star, the atmospheric composition can be determined.’

‘The analysis results confirmed the presence of water, carbon monoxide, the controversial carbon dioxide, and the newly discovered hydrogen sulfide in the atmosphere of HD 189733b.’

‘This is the first time that hydrogen sulfide has been found in an exoplanet, and it has been revealed that methane, which was speculated to be present, is not present.’

‘Furthermore, the amount of heavier elements than hydrogen and helium in the atmosphere was found to be 3-5 times higher than that in typical stars.’

‘The abundance of heavy elements such as carbon, oxygen, and sulfur serves as clues to the planetary formation environment. Ice planets like Neptune and Uranus contain more heavy elements compared to gas giants like Jupiter and Saturn, indicating that during planetary formation, they accumulated more heavy elements such as ice and rock rather than gases like hydrogen and helium.’

‘Professor Fu stated that this discovery broadens our understanding of how planets form cores and how heavy elements are added, and he said, “This research shows that the abundance of heavy elements is an important criterion for studying how planetary composition changes depending on the planet’s mass and radius.”‘

‘He also mentioned that in the future, they plan to track sulfur in more exoplanets and study how high levels of sulfur compounds affect how close the planets form to their central star, stating that “Understanding the composition of planetary atmospheres will help us find answers.”‘

“◆ Source: Nature, Guangwei Fu et al., ‘Hydrogen sulfide and metal-enriched atmosphere for a Jupiter-mass exoplanet’, https://www.nature.com/articles/s41586-024-07760-y”

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