- By Jonathan Amos
- BBC Science Correspondent
image source, NASA/ESA/CSA/J.Olmsted(STScI)
Artwork of VHS 1256b: The planet takes about 10,000 years to orbit its two parent stars
A raging dust storm has been observed on a planet outside our Solar System for the first time.
It was detected in the exoplanet known as VHS 1256b, which is about 40 light-years from Earth.
It took the amazing capabilities of the new James Webb Space Telescope (JWST) to make the discovery.
Dust particles are silicates – tiny grains composed of silicon and oxygen, which form the basis of most rocky minerals.
But the storm Webb saw was nothing like the phenomenon you’d find in an arid, desert region on our planet. It’s more of a rocky mist.
“It’s like if you took grains of sand, but finer. We’re talking about silicate grains the size of smoke particles,” explains Prof Beth Biller from the University of Edinburgh and Royal Observatory Edinburgh, UK.
“That would be the clouds in VHS 1256b, but hotter. This planet is a hot, young object. The temperature above the cloud could be similar to the temperature of a candle flame,” he told BBC News.
VHS 1256b was first identified by the UK-developed Vista telescope in Chile in 2015.
This is the so-called “super Jupiter” – a planet similar to the gas giant in our own Solar System, but much larger, perhaps 12 to 18 times the mass.
It orbits two stars at a great distance – about four times the distance of Pluto from our Sun.
Previous observations of VHS 1256b have shown that it appears red, indicating that it may have dust in its atmosphere. The Webb study confirmed this.
“This is fascinating because it illustrates how clouds on other planets can be different from the water vapor clouds we are familiar with on Earth,” said Prof Biller.
“We see carbon monoxide (CO) and methane in the atmosphere, indicating that it is hot and turbulent, with material extracted from deep.
“There are probably multiple layers of silicate grains. What we see are some very, very fine grains higher up in the atmosphere, but there may be larger grains deeper in the atmosphere.”
Telescopes have previously detected silicates in so-called brown dwarfs. These are essentially star-like objects that fail to ignite properly. But it’s a first for a planet-sized object.
To make the discovery, Webb used its Mid-Infrared Instrument (Miri), part-built in the UK, and the Near-Infrared Spectrometer (NirSpec).
They didn’t take good pictures of the planet, at least not this time. What they did was separate the light coming from VHS 1256b into its color components as a way to identify the composition of the atmosphere.
“JWST is the only telescope that can measure all these molecular and dust features together,” said Miri co-principal investigator Prof Gillian Wright, who directs the STFC UK Astronomy Technology Centre, also in Edinburgh.
“The dynamic picture of the environment of VHS 1256b provided by this study is a prime example of the discoveries enabled by using the advanced capabilities of Miri and NirSpec together.”
JWST’s main mission is to observe the pioneer stars and galaxies that first shone just a few hundred million years after the Big Bang. But one main goal is to investigate exoplanets. With Miri and NirSpec it has the tools to study their atmospheres in unprecedented detail.
Scientists hope they can even tell if some exoplanets have conditions suitable for hosting life.
James Webb is a collaborative project of the US, European and Canadian space agencies. It was launched in December 2021 and is considered the successor to the Hubble Space Telescope.
