Consider the case of so-called “hot Jupiters” — gaseous planets bigger than our own solar system’s Jupiter orbiting their parent stars closer than Mercury orbits the sun. Those locations make the planets both sizzlingly hot and difficult to study.
Nevertheless, a handful of observations by the Hubble Space Telescope turned up one puzzling find: Many hot Jupiters seem to be missing water from their atmospheres.
That prompted an international team of astronomers to mount a comparative study of 10 hot Jupiters, the largest exoplanet study to date and an indication of just how rapidly the field has grown since the detection of the first planet beyond the solar system in 1992.
Using Hubble and NASA’s infrared Spitzer space telescope, astronomers measured the planets’ atmospheres, which turned out to be much more diverse than expected.
Scientists were able to figure out that some of the hot Jupiters had clouds, while others did not. Interestingly, the cloud-free worlds showed strong signs of water, and the planets with clouds did not. The team realized that clouds, along with haze, are most likely masking the chemical fingerprints of water.
“The alternative 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,” astronomer Jonathan Fortney, with the University of California in Santa Cruz, said in a statement.
“Our results have ruled out the dry scenario, and strongly suggest that it’s simply clouds hiding the water from prying eyes,” he added.
The research is published in this week’s Nature.
From Discovery News
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