March 22 () –
Observations with the NASA/ESA/CSA James Webb Space Telescope have identified features of silicate clouds in the atmosphere of a distant planet.
The atmosphere is constantly rising, mixing and shifting during its 22-hour day, pulling hotter material up and pushing cooler material down. The resulting brightness changes are so dramatic that It is the most variable planetary mass object known to date.
The team, led by Brittany Miles of the University of Arizona, also made extraordinarily clear detections of water, methane, and carbon monoxide with Webb’s data, and found evidence of carbon dioxide. This is the largest number of molecules ever identified all at once on a planet outside of our solar system.
Cataloged as VHS 1256 b, the planet is about 40 light-years away and orbits not one, but two stars over a period of 10,000 years. “VHS 1256 b is about four times as far from its stars as Pluto is from our sun, making it a great target for Webb,” Miles said. it’s a statement. “That means the light from the planet doesn’t mix with the light from its stars.”
Higher up in its atmosphere, where silicate clouds churn, temperatures reach a blistering 815 degrees Celsius.
Within those clouds, Webb detected both larger and smaller silicate dust grains, shown in a spectrum. “The finer silicate grains in your atmosphere may look more like tiny particles in smoke,” said co-author Beth Biller of the University of Edinburgh. “Larger grains could look more like very hot, very small sand particles.”
VHS 1256 b has low gravity compared to more massive brown dwarfs, which means that its silicate clouds can appear and stay higher in its atmosphere, where Webb can detect them. Another reason why its skies are so turbulent is the age of the planet. In astronomical terms, it is quite young. Only 150 million years have passed since it was formed, and it will continue to change and cool for billions of years.
In many ways, the team considers these findings to be the first “coins” drawn from a wraith that researchers see as a treasure chest of data. In many ways, they have only begun to identify their content. “We have identified silicates, but better understanding which grain sizes and shapes match specific cloud types will require a lot of additional work,” Miles said. “This isn’t the last word on this planet, it’s the start of a large-scale modeling effort to accommodate Webb’s complex data.”
Although all of the features the team observed have been detected on other planets in other parts of the Milky Way by other telescopes, other research teams typically identified only one at a time. “No other telescope has identified so many features at once for a single target,” said co-author Andrew Skemer of the University of California, Santa Cruz. “We’re seeing many molecules in a single Webb spectrum detailing the planet’s dynamic cloud and weather systems.”
The team came to these conclusions by analyzing data known as spectra collected by two instruments aboard Webb, the Near Infrared Spectrograph (NIRSpec) and the Mid Infrared Instrument (MIRI). Since the planet orbits at such a great distance from its stars, the researchers were able to observe it directly, instead of using the transit technique or a coronagraph to take these data.
There will be much more to learn about VHS 1256 b in the coming months and years as this team, and others, continue to analyze Webb’s high-resolution infrared data. “There’s a lot of performance in a very modest amount of telescope time,” Biller added. “With only a few hours of observations, we have what seems like endless potential for additional discoveries.”
What could become of this planet billions of years from now? Since it is so far from its stars, it will get colder over time and its skies can go from cloudy to clear.
The researchers observed VHS 1256 b as part of Webb’s Early Release Science program, which is designed to help transform the astronomical community’s ability to characterize planets and the disks where they form.
The article will be published in The Astrophysical Journal Letters and is currently published on the preprint server arXiv.
