Finding clouds of water floating in the atmosphere of an alien world is a significant find. Now, astronomers have reported preliminary findings that water clouds have been detected in the atmosphere of a brown dwarf, a mere 7.3 light-years from Earth.
But don’t dream of an alien planet with white, fluffy clouds rolling over a habitable terrain, brown dwarfs are cool failed stars with thick churning atmospheres, the antithesis of a life-giving habitat (as we know it).
The brown dwarf, called WISE J0855-0714, was discovered hiding in archived data from NASA’s Wide-field Infrared Survey Telescope (WISE) and is notable in that is the coolest brown dwarf known. It has a temperature slightly lower than the freezing point of water and a mass roughly ten times that of Jupiter.
The best thing about this object is that it is an interstellar loner — it doesn’t orbit a star and drifts through space solo. This means its infrared signal could be isolated, with no host starlight overwhelming its detection.
Follow-up observations by the 6.5-meter Magellan Baade telescope in Chile by Jacqueline Faherty of the Carnegie Institution for Science in Washington, D.C., acquired 151 near-infrared images of the intriguing object, and after comparing radiation generated by the brown dwarf with atmospheric models, astronomers have announced the possible presence of water clouds high in the dwarf planet’s atmosphere. The research has been published in the Astrophysical Journal Letters.
“It’s incredibly interesting,” said Jonathan Fortney of the University of California, Santa Cruz, who was involved with the development of the brown dwarf models. “It’s tentative,” but “it’s the first evidence for water clouds” outside our solar system,” he told Science News.
Water clouds exist on Earth and Mars, and water is known to exist in the lower layers of the gas and ice giants. But until now, no other object beyond the solar system has exhibited clouds of water.
Water vapor has been detected in extrasolar planets’ atmospheres, however, but this is the first time water clouds have been spotted. Like Earth, it appears to be partly cloudy, with broken patches of water clouds, said Faherty.
This is an important discovery for brown dwarf science. These sub-stellar objects are not massive enough to sustain fusion in their cores, so they’re not stars. But they have massive un-differentiated atmospheres that make them very different from planets. They occupy a strange hinterland between the most massive gas giant planets (like Jupiter) and the smallest stars (like red dwarfs).
Although we have to wait until NASA’s James Webb Telescope launches in 2018 to acquire a spectra of the infrared radiation before we know for certain if it is indeed water, it’s a fascinating discovery that gives this particular brown dwarf a very planet-like twist.
Source: Science News