WASHINGTON: The latest weather report for the two nearest brown dwarfs, celestial bodies that are larger than planets but smaller than stars, reveals extreme and inhospitable conditions. The atmosphere on these objects is blisteringly hot, laden with toxic chemicals, and shrouded in clouds of silicate particles reminiscent of Saharan dust storms.
Utilizing observations from the James Webb Space Telescope, researchers have conducted an in-depth analysis of the atmospheric conditions of this brown dwarf pair, located about six light-years from Earth. A light-year, the distance light travels in a year, is approximately 5.9 trillion miles (9.5 trillion km).
The Webb data offered a three-dimensional perspective on how the weather changes over each brown dwarf’s rotation—seven hours for the larger and five hours for the smaller—revealing multiple cloud layers at varying atmospheric depths.
Their atmospheres, dominated by hydrogen and helium, also contain trace amounts of water vapor, methane, and carbon monoxide. The temperature at their cloud tops reaches around 1,700 degrees Fahrenheit (925 degrees Celsius), comparable to the heat of a candle flame.
“In this study, we created the most detailed ‘weather maps’ for any brown dwarf to date,” said Beth Biller, lead author of the study and an astronomer at the University of Edinburgh’s Institute for Astronomy. The study was published in the Monthly Notices of the Royal Astronomical Society.
Brown dwarfs emit their own light due to their heat, similar to glowing embers in a fire, but lack the nuclear fusion that powers stars. They often form from large clouds of gas and dust like stars but don’t achieve sufficient mass to ignite nuclear fusion. Their composition is akin to gas giant planets like Jupiter, and their mass can be up to 80 times greater.
The two brown dwarfs observed by Webb formed around 500 million years ago, each with a diameter comparable to Jupiter’s. One is 35 times more massive than Jupiter, while the other is 30 times.
Webb’s observations captured how the light from these brown dwarfs varied as different atmospheric features rotated into view, indicating fast rotation that influences their weather patterns. “If you could directly see the cloud-top structure, you’d likely observe bands and vortices similar to Jupiter’s Great Red Spot,” Biller noted.
Future studies could apply similar techniques to investigate weather on potentially habitable exoplanets, planets outside our solar system. Brown dwarfs, numbering around 1,000 known examples compared to over 5,000 known exoplanets, are relatively common.
“The atmospheres of brown dwarfs are highly complex,” said co-author Johanna Vos of Trinity College Dublin. “Webb provides a huge leap forward in our understanding by offering unprecedented wavelength range and sensitivity, allowing us to monitor the atmosphere from very deep to very shallow.”
These advancements in atmospheric study mark a significant step in our understanding of brown dwarfs and potentially, exoplanetary weather systems.
I am an accomplished graduate of Strategic Studies, driven by a fervent dedication to comprehending global affairs and devising impactful strategies. Equipped with a comprehensive skill set encompassing research, critical thinking, and persuasive communication, I possess a distinctive viewpoint and an unwavering commitment to fostering inclusive decision-making processes. As a versatile individual, I excel in collaborating with diverse groups in various settings, leveraging my strong interpersonal abilities to adapt seamlessly to new environments and surmount any challenges that arise. With a passion for contributing to strategic initiatives, I am eager to leverage my expertise and drive to effect positive change within the field.
