Posted on 01/10/2024 12:30:19 AM PST by Red Badger
Infrared emission from methane suggests atmospheric heating by auroral processes.
Astronomers using NASA’s James Webb Space Telescope have found a brown dwarf (an object more massive than Jupiter but smaller than a star) with infrared emission from methane, likely due to energy in its upper atmosphere. This is an unexpected discovery because the brown dwarf, W1935, is cold and lacks a host star; therefore, there is no obvious source for the upper atmosphere energy. The team speculates that the methane emission may be due to processes generating aurorae.
These findings are being presented at the 243rd meeting of the American Astronomical Society in New Orleans.
To help explain the mystery of the infrared emission from methane, the team turned to our solar system. Methane in emission is a common feature in gas giants like Jupiter and Saturn. The upper-atmosphere heating that powers this emission is linked to aurorae.
This artist concept portrays the brown dwarf W1935, which is located 47 light-years from Earth. Astronomers using NASA’s James Webb Space Telescope found infrared emission from methane coming from W1935. This is an unexpected discovery because the brown dwarf is cold and lacks a host star; therefore, there is no obvious source of energy to heat its upper atmosphere and make the methane glow. The team speculates that the methane emission may be due to processes generating aurorae, shown here in red. NASA, ESA, CSA, and L. Hustak (STScI) On Earth, aurorae are created when energetic particles blown into space from the Sun are captured by Earth’s magnetic field. They cascade down into our atmosphere along magnetic field lines near Earth’s poles, colliding with gas molecules and creating eerie, dancing curtains of light. Jupiter and Saturn have similar auroral processes that involve interacting with the solar wind, but they also get auroral contributions from nearby active moons like Io (for Jupiter) and Enceladus (for Saturn).
For isolated brown dwarfs like W1935, the absence of a stellar wind to contribute to the auroral process and explain the extra energy in the upper atmosphere required for the methane emission is a mystery. The team surmises that either unaccounted internal processes like the atmospheric phenomena of Jupiter and Saturn, or external interactions with either interstellar plasma or a nearby active moon, may help account for the emission.
A Detective Story The aurorae’s discovery played out like a detective story. A team led by Jackie Faherty, an astronomer at the American Museum of Natural History in New York, was awarded time with the Webb telescope to investigate 12 cold brown dwarfs. Among those were W1935 – an object that was discovered by citizen scientist Dan Caselden, who worked with the Backyard Worlds zooniverse project – and W2220, an object that was discovered using NASA’s Wide Field Infrared Survey Explorer. Webb revealed in exquisite detail that W1935 and W2220 appeared to be near clones of each other in composition. They also shared similar brightness, temperatures, and spectral features of water, ammonia, carbon monoxide, and carbon dioxide. The striking exception was that W1935 showed emission from methane, as opposed to the anticipated absorption feature that was observed toward W2220. This was seen at a distinct infrared wavelength to which Webb is uniquely sensitive.
“We expected to see methane because methane is all over these brown dwarfs. But instead of absorbing light, we saw just the opposite: The methane was glowing. My first thought was, what the heck? Why is methane emission coming out of this object?” said Faherty.
The team used computer models to infer what might be behind the emission. The modeling work showed that W2220 had an expected distribution of energy throughout the atmosphere, getting cooler with increasing altitude. W1935, on the other hand, had a surprising result. The best model favored a temperature inversion, where the atmosphere got warmer with increasing altitude. “This temperature inversion is really puzzling,” said Ben Burningham, a co-author from the University of Hertfordshire in England and lead modeler on the work. “We have seen this kind of phenomenon in planets with a nearby star that can heat the stratosphere, but seeing it in an object with no obvious external heat source is wild.”
Image: Spectra W1935 vs W2220
Astronomers used NASA’s James Webb Space Telescope to study 12 cold brown dwarfs. Two of them – W1935 and W2220 – appeared to be near twins of each other in composition, brightness, and temperature. However, W1935 showed emission from methane, as opposed to the anticipated absorption feature that was observed toward W2220. The team speculates that the methane emission may be due to processes generating aurorae. NASA, ESA, CSA, and L. Hustak (STScI) Clues from our Solar System For clues, the team looked in our own backyard, to the planets of our solar system. The gas giant planets can serve as proxies for what is seen going on more than 40 light-years away in the atmosphere of W1935.
The team realized that temperature inversions are prominent in planets like Jupiter and Saturn. There is still ongoing work to understand the causes of their stratospheric heating, but leading theories for the solar system involve external heating by aurorae and internal energy transport from deeper in the atmosphere (with the former a leading explanation).
Brown Dwarf Aurora Candidates in Context This is not the first time an aurora has been used to explain a brown dwarf observation. Astronomers have detected radio emission coming from several warmer brown dwarfs and invoked aurorae as the most likely explanation. Searches were conducted with ground-based telescopes like the Keck Observatory for infrared signatures from these radio-emitting brown dwarfs to further characterize the phenomenon, but were inconclusive.
W1935 is the first auroral candidate outside the solar system with the signature of methane emission. It’s also the coldest auroral candidate outside our solar system, with an effective temperature of about 400 degrees Fahrenheit (200 degrees Celsius), about 600 degrees Fahrenheit warmer than Jupiter.
In our solar system the solar wind is a primary contributor to auroral processes, with active moons like Io and Enceladus playing a role for planets like Jupiter and Saturn, respectively. W1935 lacks a companion star entirely, so a stellar wind cannot contribute to the phenomenon. It is yet to be seen whether an active moon might play a role in the methane emission on W1935.
“With W1935, we now have a spectacular extension of a solar system phenomenon without any stellar irradiation to help in the explanation.” Faherty noted. “With Webb, we can really ‘open the hood’ on the chemistry and unpack how similar or different the auroral process may be beyond our solar system,” she added.
The James Webb Space Telescope is the world’s premier space science observatory. Webb is solving mysteries in our solar system, looking beyond to distant worlds around other stars, and probing the mysterious structures and origins of our universe and our place in it. Webb is an international program led by NASA with its partners, ESA (European Space Agency) and the Canadian Space Agency.
Webb Ping!......................
I like the LEDs at its North Pole.
Each one would be larger than the Earth..................
Why is NASA using the Webb telescope to spy on introverted short Hispanics? And who is Aurorae?
Upon reading the title here, I could not help but recall the Fantasy Island TV series, “The plane ! The plane !” shouted by Tatoo.
Since methane is a ‘fossil fuel’, this was likely a result of all the dead dinosaurs on the ‘brown dwarf’.
“Did the door suddenly blow off or did it first ‘spring a leak’, allowing the cabin to depressurize without passengers being sucked out?”
A number of factors:
1) This particular aircraft was known to have “pressurization problems” and with that, Alaska was afraid to fly it to Hawaii (definitely a Gold Star for Alaska).
2) So, yes, the leak was there.
3) There wasn’t a passenger directly adjacent to the blow-out (just luck on that one).
4) One mom had to tightly hang on to her twerp to keep him (or her) from being sucked out, but she lost her cell phone (your call regarding which she should have protected more).
5) My guess is that the passengers most at risk still had their seat belts on, thus preventing them from trying to imitate Evil Knievel.
Thanks Red Badger.
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NASA will have to erase this from the official record.
The word “dwarf” has been banned.
The correct term is “little person” or “person of short stature”.
For astronomical bodies these would be “star of short stature” or “little star”.
Failure to abide by these rules of tolerance is an act of insurrection and is subject to prosecution by the state of California and the countries of Canada and the Ukraine.
However, these rules may go into effect elsewhere on the planet at any time.
Stay tuned to Wikipedia for upcoming guidance on your future obedience as a loyal citizen of the planet.
;-)
Who would have guessed you would find “fossil fuels” on a Brown Dwarf star.
So we see now its NOT Fusion which power stars but dead dinosaurs.
Who would have guessed?
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