New observations of a brown dwarf known as WISE 0855 has revealed evidence of water clouds in the body’s atmosphere, marking the first time astronomers have been able to detect such signals from an object beyond our solar system.
According to Space.com, WISE 0855 is a “failed star” located 7.2 light years from Earth. It is the coldest known object located outside of the solar system, the website said, and is barely visible at infrared wavelengths when viewed using Earth’s most powerful ground-based telescopes.
Now, a team led by Andrew Skemer, an assistant professor of astronomy and astrophysics at the University of California-Santa Cruz analyzed WISE 0855 using the Gemini North telescope in Hawaii and captured the first details of the brown dwarf’s composition and chemistry, as well as “strong evidence” that clouds of water or water ice surround the extrasolar object.
“WISE 0855 is our first opportunity to study an extrasolar planetary-mass object that is nearly as cold as our own gas giants,” Skemer noted earlier this week in a statement. “We would expect an object that cold to have water clouds, and this is the best evidence that it does.”
Research reveals similarities between brown dwarf, Jupiter
Five times more massive than Jupiter, WISE 0855 is both too large to be a planet and too small to trigger the internal fusion reactions necessary to become a star. It was first discovered in 2014 using date from the NASA Wide-field Infrared Survey Explorer (WISE) spacecraft (hence its name), and later research found early evidence of atmospheric water clouds.
In the new study, Skemer and his colleagues used the Gemini North telescope and the Gemini Near Infrared Spectrograph to observe the brown dwarf for a total span of about 14 hours over 13 nights. While the object is too faint to be studied using conventional spectroscopy at optical or near-infrared wavelengths, the researchers were able to take advantage of a narrow window created thanks to thermal emissions from its deep atmosphere.
Skemer explained that WISE 0855 is “five times fainter than any other object detected with ground-based spectroscopy at this wavelength. Now that we have a spectrum, we can really start thinking about what’s going on in this object. Our spectrum shows that WISE 0855 is dominated by water vapor and clouds, with an overall appearance that is strikingly similar to Jupiter.”
Specifically, their findings – which have been published in the Astrophysical Journal Letters – revealed that the brown dwarf’s spectrum appears to feature water-absorption features similar to those found in Jupiter’s atmosphere, according to Space.com. However, the object has much less phosphine (a compound of phosphorous and hydrogen created in the extremely hot interior of an object) than Jupiter, suggesting that it has a less turbulent atmosphere than the gas giant.
“The spectrum allows us to investigate dynamical and chemical properties that have long been studied in Jupiter’s atmosphere, but this time on an extrasolar world,” said Skemer, who worked on the study along with colleagues from NASA, Bucknell University, the Carnegie Institution of Washington and the Gemini Observatory.
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Image Credit: Joy Pollard, Gemini Observatory/AURA
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