The James Webb Space Telescope (JWST) has discovered stormy weather in the skies of two brown dwarfs, the most detailed weather report yet from such “failed stars”.
The two brown dwarfs formed a binary pair called WISE 1049AB, which was discovered by NASA's Wide-field Infrared Survey Explorer (WISE) in 2013; the two were only 6.5 light years Stay away from us. They are the closest brown dwarfs to us sunmaking it an excellent target for the James Webb Space Telescope's powerful infrared instrument.
A brown dwarf is an object that is not massive enough to ignite the Earth nuclear fusion Converts hydrogen into helium in its core and becomes a mature Star – but is also thought to be too large to be a planet, and is thought to have formed like a star (through the gravitational collapse of a cloud of molecular gas). Therefore, brown dwarfs are considered to be the missing link between the two. gas giant planet like Jupiterand the lowest mass stars, M dwarf.
Previous observations have explored the atmospheres of various brown dwarfs, but they were always limited to time-averaged snapshots, meaning we couldn't see how things in a brown dwarf's atmosphere change over time. However, brown dwarfs are rapidly rotating bodies – WISE 1049A rotates on its axis every 7 hours, B every 5 hours – and their atmospheric conditions change over time, meaning that previous observations The influence of these celestial bodies was not taken into account.
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However, JWST does have the ability to detect these changes over time. A team led by Beth Biller of the University of Edinburgh observed WISE 1049AB for 8 hours using JWST's mid-infrared instrument (MIRI), and then immediately used the near-infrared spectrometer (NIRSpec) for another 7 hours.
The researchers found that both brown dwarfs are covered in turbulent clouds, likely composed of silicate grains, and have sweltering temperatures between 875 degrees Celsius (1,610 degrees Fahrenheit) and 1,026 degrees Celsius (1,880 degrees Fahrenheit). In other words, the winds from the brown dwarf are blowing hot sand. The absorption properties of carbon monoxide, methane and water vapor were also determined.
Interestingly, each brown dwarf's light curve (a plot of each brown dwarf's brightness over time) shows considerable variability. This was interpreted as stormy conditions blowing clouds at different heights, and gaps between these clouds allowing deeper layers of the atmosphere to be seen. The light curves also show peaks at specific wavelengths – carbon monoxide at 2.3 microns and 4.2 microns (millionths of a meter), methane at 3.3 microns, and silicate particles tentatively at 8.3 microns to 8.5 microns.
Buehler's team interpreted the peaks in these wavelengths as indicating three distinct layers in which the atmospheric pressure of each brown dwarf changes significantly. The deep layers generate signals larger than 2.3 microns but smaller than 8.5 microns, the middle altitude layers absorb light between 2.3 and 4.2 microns, and the high altitude layers exhibit signals between 4.2 and 8.5 microns.
These findings show that, for the first time, JWST is able to detect vertical profiles of brown dwarf atmospheres (i.e., conditions at different depths), and in fact, there is no reason why JWST has to stop there. As the research paper describing the findings concludes: “This is the first study of its kind, but it will not be the last – over the next few observing cycles, JWST will transform our understanding of brown dwarfs and young giant stars. understanding. exoplanet atmosphere.
“Our findings suggest that we are on the cusp of changing our understanding of the world well beyond our own world,” Buehler said in a report. statement. “Insights such as these can help us understand not only the conditions of objects like brown dwarfs, but also the conditions of giant exoplanets beyond our own. solar system. Eventually, the technology we've perfected here may be able to detect weather for the first time habitable planet Just like our own star, it orbits other stars.
The research results were published in the July 15 issue of ” Royal Astronomical Society monthly notices.
