Artist's illustration of how the nearby brown dwarf WISE 0855 might appear if viewed close-up in infrared light.

(Joy Pollard, Gemini Observatory/AURA)

At a Glance

Scientists discover compelling evidence of a gas giant outside our solar system.Brown dwarf WISE 0855 shares many similarities with Jupiter.Coldest known body outside the solar system.

Astronomers have found the first strong evidence of water clouds on a heavenly body outside our solar system.

Scientists at the University of California, Santa Cruz, said that recent observations of a frigid brown dwarf called WISE 0855, which lies 7.2 light-years from Earth, suggest that the "failed star," another name for a dwarf planet, has clouds of water, or water ice, in its atmosphere.

"We would expect an object that cold to have water clouds, and this is the best evidence that it does," study lead author Andrew Skemer, an assistant professor of astronomy and astrophysics at the University of California, Santa Cruz, said in the statement.

Similar to Jupiter

The coldest known object outside of our solar system, the brown dwarf is similar to Jupiter in many respects. While its mass is roughly five times that of the largest planet in the solar system, its temperature is about 250 Kelvin, or minus 10 degrees Fahrenheit, making it nearly as cold as Jupiter, which is 130 Kelvin.

"WISE 0855 is our first opportunity to study an extrasolar planetary-mass object that is nearly as cold as our own gas giants," Skemer said.

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Noting that observations of the brown dwarf provided tentative indications of water clouds based on very limited photometric data, Skemer saidobtaining a spectrum, which separates the light from an object into its component wavelengths, is the only way to detect an object's molecular composition.

Using the Gemini North telescope in Hawaii over 13 nights for a total of about 14 hours, the researchers were able to obtain an infrared spectrum of WISE 0855, which provided the first details of the object's composition and chemistry.

"It's five times fainter than any other object detected with ground-based spectroscopy at this wavelength," Skemer said. "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."

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