Astronomers Track Down a Bizarre Exoplanet Named 'WASP-96b' Which Has Zero Clouds

Monday, 07 May 2018 - 8:27PM
Space
Astronomy
Monday, 07 May 2018 - 8:27PM
Astronomers Track Down a Bizarre Exoplanet Named 'WASP-96b' Which Has Zero Clouds
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NASA, ESA & G. Bacon
With all the exoplanets we've been discovering lately, it's tough to actually find a clear sky in all these alien atmospheres.

Until now, at least - a team of astronomers, led by Nikolay Nikolov from the University of Exeter, were able to get a close enough look at the distant planet WASP-96b (exoplanets don't typically have creative names) and found that it was completely free of clouds in its atmosphere, allowing the team to get a much more detailed reading of how the planet looks closer to its surface.

WASP-96b is a "hot Saturn" planet - that's exactly what it sounds like, a hot gas giant very similar to Saturn - orbiting a star about 980 lightyears away inside the Phoenix constellation. Using the ESO's Very Large Telescope in Chile, the team got a good look at the exoplanet while it was "transiting" or passing in front of its star.

Since exoplanets are distant, small, and none too bright, watching for transit events (where a star's brightness dips as something passes in front of it) is the key to discovering these planets in other solar systems.



Because of its cloudless skies, the team managed to get a really good look at the planet's composition, and found it contained tons of sodium. That may not sound exciting, but it's impossible to pick up spectral characteristics of sodium atoms in a distant planet with a thick atmosphere, even though hot gas giants have long been thought to contain them.

Now, we have some proof that sodium does exist on planets like this. According to Nikolov, who said the following in a statement from the University of Exeter:

Opening quote
"We've been looking at more than twenty exoplanet transit spectra. WASP-96b is the only exoplanet that appears to be entirely cloud-free and shows such a clear sodium signature, making the planet a benchmark for characterization. Until now, sodium was revealed either as a very narrow peak or found to be completely missing. This is because the characteristic 'tent-shaped' profile can only be produced deep in the atmosphere of the planet and for most planet clouds appear to get in the way."
Closing quote


So it may not be an exoplanet capable of supporting life, or one with weird gravity-defying winds like other exoplanets we've found, but it's a fascinating one all the same.

And now that NASA's Transiting Exoplanet Survey Satellite (TESS) has finally launched, we should be finding plenty more soon.
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