getty The same team of researchers that last week took the James Webb Space Telescope’s (JWST) first direct image of a planet outside our solar system have confirmed the presence of smoke-like silicon clouds in the atmosphere of another. Speculated for many years, the finding published in a new (non-peer-reviewed) paper reveals that an exoplanet called VHS 1256 b has a violent and turbulent atmosphere that is filled with clouds. Except these clouds aren’t made of water vapor droplets, but of smoke-like silica particles. “A better way to think of these clouds is as objects made up of tiny particles … except that these silica clouds are made of the same stuff that grains of sand are made of,” said Sasha Hinkley, Deputy Professor in the Department of Physics & Astronomy at the University of Exeter and Principal Investigator for one of JWST’s 13 Early Release Science Programmes. Astronomers who model exoplanet atmospheres using computers have predicted for decades that these smoke-like particles should be present in those atmospheres, but only JWST has the wavelength coverage to detect them definitively. In addition to the clouds, the team also found carbon dioxide in the atmosphere of VHS 1256 b—just days after JWST first detected carbon dioxide around another exoplanet. This “second time” didn’t make the headlines, which helps put these findings into context. JWST is currently being completed as it is used to make the first infrared observations of the universe, so expect many “firsts” in the coming months. For example, they also revealed a turbulent atmosphere in VHS 1256 b. “In a quiescent atmosphere, there is an expected ratio of, say, methane to carbon monoxide,” Hinckley said. “But in many exoplanet atmospheres we find that this ratio is very skewed, suggesting that there is turbulent vertical mixing in these atmospheres, drawing carbon dioxide up from deep to mix with methane higher in the atmosphere.” This discovery of “chemistry disequilibrium” in a distant exoplanet is itself a landmark discovery for JWST. VHS 1256 b is quite an odd place. Orbiting not one, but two brown dwarf stars that themselves orbit each other, the planet does not orbit its binary host in a circle, but rather in a very oval “eccentric” orbit. It is 72 light-years from the solar system in the constellation Corvus. It is somewhere between 12 and 16 Jupiter masses, which is so large that it is a failed brown dwarf star candidate rather than a planet. So the paper actually refers to it as a “planetary mass companion” rather than just a planet. “It’s definitely not terrestrial,” Hinckley said. “It looks much more like a gas giant, super-Jupiter object.” Either way, this object is about 360 times our Earth-Sun distance away from its host stars, so it takes 17,000 years to orbit. Webb is the most ambitious and complex space science telescope ever built, with a massive 6.5m primary mirror that will be able to detect the faint light of distant stars and galaxies. It is designed exclusively to detect infrared light emitted by distant stars, planets, and clouds of gas and dust. I wish you clear skies and open eyes.
