The James Webb Space Telescope (JWST) has discovered stormy weather in the skies above two brown dwarfs, the most detailed weather forecast yet from such “failed stars.”
two Brown dwarf It formed a binary star called WISE 1049AB. National Aeronautics and Space Administration (NASA)Following the launch of the Wide-field Infrared Survey Explorer (WISE) satellite in 2013, the two satellites sank to a height of just 6.5 metres. Light years It is far away from Earth. It is the closest brown dwarf to Earth. Sunand therefore, James Webb Space TelescopePowerful infrared equipment.
A brown dwarf is an object that does not have enough mass to outpower the Sun. Nuclear fusion Converting hydrogen in the nucleus to helium, Star — But they are thought to be too large to be planets, and are thought to form in the same way as stars (by the gravitational collapse of a cloud of molecular gas). Gas giants like Jupiterand the least massive star, M-dwarf.
Previous observations have looked at the atmospheres of various brown dwarfs, but they have always been limited to time-averaged snapshots, meaning they have not been able to see how the atmospheres of brown dwarfs change over time. However, brown dwarfs rotate quickly (WISE 1049A rotates on its axis every 7 hours, while B rotates on its axis every 5 hours), meaning that the state of their atmospheres can change over time. This means that previous observations, which did not take into account the evolution of celestial objects, may have missed many fluctuations.
But JWST has the ability to detect these changes over time: A team led by Beth Biller of the University of Edinburgh observed WISE 1049AB for eight hours with JWST’s Mid-Infrared Instrument (MIRI), followed immediately by a further seven hours with the Near-Infrared Spectrometer (NIRSpec).
The researchers found that both brown dwarfs are likely covered in intense clouds of silicate grains, sweltering at temperatures between 875 degrees Celsius (1,610 degrees Fahrenheit) and 1,026 degrees Celsius (1,880 degrees Fahrenheit). In other words, hot sand is being blown into the brown dwarfs’ winds. Absorption signatures for carbon monoxide, methane, and water vapor were also identified.
Interestingly, the light curves of each brown dwarf (a graph of their brightness over time) show considerable variation. This is interpreted as storm conditions blowing clouds to different altitudes, leaving gaps between the clouds that reveal the deeper atmosphere. The light curves show peaks at specific wavelengths: carbon monoxide at 2.3 and 4.2 microns (millionths of a meter), methane at 3.3 microns, and silicate particles tentatively at 8.3 to 8.5 microns.
Biller’s team interprets these wavelength peaks as indicating three distinct layers with large variations in atmospheric pressure in each brown dwarf: a deep layer that produces a signal above 2.3 microns but below 8.5 microns, a mid-altitude layer that absorbs light between 2.3 and 4.2 microns, and a high-altitude layer that shows a signal between 4.2 and 8.5 microns.
This discovery demonstrates that JWST has the capability to study the vertical profile of a brown dwarf’s atmosphere (i.e., its condition at different depths) for the first time, and indeed there is no reason for JWST to stop there. The research paper concludes about the discovery: “This is the first study, but it will not be the last. Over the next few observing cycles, JWST will transform our understanding of both brown dwarfs and young giants.” Exoplanets atmosphere.”
“Our findings show that we are on the brink of transforming our understanding of a world far beyond our own,” Biller said. statement“Such insights will help us understand the conditions of objects like brown dwarfs, as well as giant exoplanets outside our solar system. Solar SystemUltimately, the technology we’re improving here will Habitable planets It’s a planet, like ours, that orbits another star.”
The findings were released on July 15th. Monthly Bulletin of the Royal Astronomical Society.
