Produced by: Tarun Mishra
Sulphur dioxide has been detected in the atmosphere of the exoplanet GJ 3470b, a surprising find for a planet of its size. This discovery was made using the James Webb Space Telescope (JWST).
GJ 3470b, located 96 light-years from Earth, is categorized as a "hot Neptune." It has a mass 13.9 times that of Earth and a diameter about 40% that of Jupiter.
The planet orbits its star at a steep 89-degree incline, looping over the star's poles every three-and-a-third days, which is unusual for planet formation.
Credit: Department of Astronomy, UW–Madison
GJ 3470b has an atmospheric temperature of 325 degrees Celsius. Unlike Neptune, which is much colder, GJ 3470b's atmosphere is predominantly made of hydrogen and helium, with significant amounts of carbon dioxide, methane, and water vapor.
Current theories suggest that GJ 3470b formed close to its star as a rocky planet before gaining a thick hydrogen-helium atmosphere. The presence of sulphur dioxide challenges and enriches these theories.
Credit: NASA
JWST used transmission spectroscopy to detect sulphur dioxide, analysing how starlight passing through the planet’s atmosphere was absorbed by different molecules, revealing dark absorption lines in the spectrum.
The sulphur dioxide likely originates from hydrogen sulphide, which, due to the planet's proximity to its star, is broken down by ultraviolet light, leading to the formation of sulphur dioxide.
Credit: NASA
GJ 3470b is losing its atmosphere due to stellar winds and ultraviolet radiation, with an estimated 40% of its original mass already lost. This process is ongoing, with hydrogen gas trailing behind the planet.
The detection of sulphur dioxide in such a small exoplanet provides new insights into planet formation and atmospheric evolution, offering clues about the chemical processes in extreme environments. The findings were presented at the 244th meeting of the American Astronomical Society and accepted for publication in Astrophysical Journal Letters.