The James Webb Space Telescope (JWST) has found direct evidence of clouds made from sand-like substances on a distant world.
Brown dwarfs are large balls of gas, more massive than planets but without enough mass and pressure from gravity to start nuclear fusion like stars, giving them a dull glow in mostly the infrared range. To date, all our observations of these failed stars had been in a narrow wavelength of light, limiting our understanding of their chemical composition.
Now, at the University of Edinburgh, UK, and her colleagues have used JWST to capture the signature of VHS 1256 b, a brown dwarf that is almost 20 times more massive than Jupiter and just under the threshold for nuclear fusion.
Advertisement
鈥淛WST just, again, performed magnificently. The spectrum is utterly gorgeous,鈥� says Biller.
The telescope鈥檚 ability to observe across a wide range of infrared means the team could capture much more detail from the brown dwarf鈥檚 atmosphere, identifying molecules of water, methane and carbon dioxide; metals like sodium and potassium; and clouds made from silica-based particles, similar to sand.
While astronomers had previously inferred the existence of silicate dust clouds in some brown dwarfs, based on their colours, this is the first direct evidence of these clouds.
These silicates are probably molecules like enstatite and forsterite, which make up part of Earth鈥檚 mantle. On VHS 1256 b, they instead take the form of tiny particulates floating through the atmosphere like smoke, says team member at the University of Exeter, UK. 鈥淭hese have been hypothesised for many, many years, but JWST has the range of wavelengths that can definitively detect these things.鈥�
鈥淢y mental picture is that if you put out your hand you would feel sand, like when it is super windy at the beach,鈥� says at the University of Arizona. 鈥淔or us to see the feature in the spectrum means that at least some of the particles are small, sub micron, so like very fine grained dust, but some will be bigger, up to beach sand size.鈥�
Reference:
Sign up to our free Launchpad newsletter for a voyage across the galaxy and beyond, every Friday
