A serendipitous discovery is revolutionizing our understanding of gas giant atmospheres, including those of Jupiter and Saturn. In 2020, a citizen scientist participating in NASA's Backyard Worlds: Planet 9 project stumbled upon a peculiar brown dwarf, dubbed "The Accident," due to its unexpected properties. This unusual object, a celestial body falling between a planet and a star, possesses a unique mix of characteristics typically associated with both young and old brown dwarfs.
The Accident's unusual nature made it an ideal target for NASA's James Webb Space Telescope (JWST). JWST's powerful observational capabilities revealed a surprising atmospheric component: silane (SiH4), a simple silicon molecule. The detection of silane in The Accident is groundbreaking; this molecule has been hypothesized to exist in gas giants like Jupiter and Saturn, but has evaded detection until now.
Scientists believe silicon exists in Jupiter and Saturn, but is likely hidden deep within their atmospheres. It's theorized that silicon bonds with oxygen to form oxides that seed cloud formation, sinking far below visible layers of water vapor and ammonia. The expectation was that lighter silicon molecules, like silane, might reside higher in the atmosphere, but their absence had puzzled researchers.
The Accident, estimated to be 10 to 12 billion years old, formed in a universe primarily composed of hydrogen and helium with trace elements. Its relative lack of oxygen, compared to more recently formed celestial bodies, allowed the silicon to bond with hydrogen, creating silane. This contrasts with younger gas giants, where readily available oxygen would dominate the chemical reactions and prevent silane formation.
This discovery highlights the importance of studying extreme objects like The Accident to understand more commonplace ones. Brown dwarfs, while different from gas giants, provide valuable insights into planetary atmospheres because they're often easier to observe than exoplanets, whose light is often obscured by their host stars. The study's lead author, Dr. Faherty of the American Museum of Natural History, emphasizes that these findings provide valuable experience for analyzing complex atmospheric data on potentially habitable exoplanets in the future, even if the specific element under study differs.
The research, published in Nature, confirms the formation of silane in brown dwarf atmospheres. The lack of silane in other gas giants and brown dwarfs suggests that oxygen abundance plays a critical role in the chemical processes within their atmospheres. This accidental discovery underscores the unexpected insights that can arise from serendipitous observations and the continued power of citizen science in advancing our understanding of the universe.
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Originally published at: https://www.nasa.gov/missions/webb/nasa-study-celestial-accident-sheds-light-on-jupiter-saturn-riddle/
