Hot clouds of silicate sand have been discovered on a young planet orbiting two distant stars, along with clear signatures of water, methane, carbon monoxide and - potentially - carbon dioxide.
The exoplanet - known as VHS 1256 b - is just 40 lightyears from Earth and orbits two stars over a 10,000-year period.
Using the James Webb Space Telescope, a team of astronomers led by Brittany Miles of the University of Arizona have discovered silicate cloud features in the young gas giant's atmosphere.
They have also confirmed the presence of water, methane and carbon monoxide and found evidence of carbon dioxide, making it the largest number of molecules ever identified all at once on a planet beyond our Solar System.
The planet's atmosphere is continuously rising and churning during its 22-hour day, pushing hotter material upwards and colder material down.
This causes changes in the planet's brightness, so much so that it is the most variable planetary-mass object so far discovered.
High up in VHS 1256 b's atmosphere, temperatures reach 830°C, and this is where the team behind the study discovered larger and smaller silicate dust grains within the clouds.
"The smaller silicate grains in its atmosphere may be more like tiny particles as in smoke," says study co-author Beth Biller of the University of Edinburgh.
"The larger grains might be more like very hot, very small sand particles."
VHS 1256 b is relatively young, having formed just 150 million years ago.
As a result, heat from its formation process is still present, which is part of the reason its atmosphere is so turbulent.
"VHS 1256 b is about four times farther from its stars than Pluto is from our Sun, which makes it a great target for the JWST," says Miles.
"That means the planet’s light is not mixed with light from its stars."
This distance from the host star meant that information and data from the exoplanet was not disturbed by the star's light, giving the team a greater chance at learning more about the planet's composition.
They studied spectra of light from the planet using the Webb Telescope's Near-Infrared Spectrograph (NIRSpec) and the Mid-Infrared Instrument (MIRI).
"No other telescope has identified so many features at once for a single target," says co-author Paul Mollière of the Max Planck Institute for Astronomy (MPIA) in Heidelberg, Germany.
"We’re seeing many molecules in a single spectrum from the JWST that detail the planet’s dynamic cloud and weather systems."
"We’ve isolated silicates, but better understanding which grain sizes and shapes match specific types of clouds is going to take a lot of additional work," says Elisabeth Matthews, also from MPIA.
"This is not the final word on this planet – it is only the beginning of a large-scale modeling effort to understand JWST’s complex data."
Read more about this story at www.mpia.de.
Read the full paper at arxiv.org/abs/2209.00620.
