Study: Many Exoplanets May Be Hiding Water In Clouds

Exoplanets May Be Hiding Water
An illustration of ten of the newly-analyzed hot-Jupiters. Photo by ESA/Hubble/NASA

EXETER, England, Dec. 14 (UPI) — A new survey of exoplanets called hot-Jupiters — gas giants resembling Jupiter, only hotter — suggests they aren’t as dry as previously thought.

Examining faraway worlds in detail is quite difficult. Astronomers are forced to intuit information about an exoplanet’s composition and atmosphere by analyzing the way the light from its host star is scattered as the planet travels across its face.

This analysis has previously shown hot-Jupiters to relatively dry, much drier than expected. The findings run counter to the models explaining the evolution of our own early solar system, where water was relatively abundant.

But a new look at exoplanet data from the Hubble and Spitzer space telescopes suggests water may be simply hiding in the thick clouds that surround many hot-Jupiters.

The findings were published this week in the journal Nature.

Studying the signatures of scattered solar energy left by passing exoplanets isn’t easy, especially when the planets are so close to their host suns.

But in combining observations from Hubble and Spitzer, astronomers gained a more accurate picture of each exoplanet and their atmospheres.

“I’m really excited to finally ‘see’ this wide group of planets together, as this is the first time we’ve had sufficient wavelength coverage to be able to compare multiple features from one planet to another,” lead study author David Sing, an astronomer at the University of Exeter, said in a press release. “We found the planetary atmospheres to be much more diverse than we expected.”

Among the diversity, Sing and his colleagues found a correlation between exoplanets and hazy clouds. While exoplanets without clouds tended to boast water signatures, those with little evidence of water tended to host hazy atmospheres.

“The alternative to this is that planets form in an environment deprived of water — but this would require us to completely rethink our current theories of how planets are born,” said co-author Jonathan Fortney, a researcher with the University of California, Santa Cruz.

“Our results have ruled out the dry scenario, and strongly suggest that it’s simply clouds hiding the water from prying eyes.”



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