NASA's James Webb Space Telescope (JWST) has made a groundbreaking discovery by detecting water vapor in the atmosphere of the exoplanet TOI-421 b. This sub-Neptune, located approximately 244 light-years from Earth, is offering scientists unprecedented insights into the composition and formation of this common type of planet.
TOI-421 b boasts a scorching atmospheric temperature of 1,340 degrees Fahrenheit (727 degrees Celsius). JWST's observations not only confirmed the presence of water vapor but also revealed tentative signatures of carbon monoxide and sulfur dioxide. Surprisingly, the data showed no evidence of methane or carbon dioxide. Furthermore, scientists found a significant amount of hydrogen in the planet's atmosphere.
This lightweight, hydrogen-rich atmosphere closely resembles the composition of TOI-421 b's host star. This suggests a formation process akin to the giant planets in our solar system, challenging existing theories about the evolution of sub-Neptune planets. The absence of haze, typically expected in sub-Neptunes, allowed for a clear view of the atmospheric composition. This discovery is particularly exciting because sub-Neptunes are the most common type of exoplanet, yet there are none in our solar system.