Supersonic winds swirling through Jupiter sized exoplanets atmosphere

Supersonic winds more than six times faster than those on Jupiter are blasting through the atmosphere of a Jupiter sized exoplanet 60 light years away in the constellation Vulpecula.

Washington, May 10 : Supersonic winds more than six times faster than those on Jupiter are blasting through the atmosphere of a Jupiter sized exoplanet 60 light years away in the constellation Vulpecula.

The Spitzer Space Telescope team that mapped the weather on the gas giant HD 189733b said the exoplanet's wind speeds probably exceeded the speed of sound.

"The exoplanet's wind speeds probably exceed the speed of sound, and the speed of sound on these planets is 10 times faster than on Earth, so that's saying something.

The speed of sound in HD 189733b's atmosphere is about three kilometres per second, or 6,700 mph," said Adam Showman of the University of Arizona Lunar and Planetary Laboratory (LPL).

For their study, Showman and LPL research associate Curtis Cooper analyzed Spitzer data on planet HD 189733b using the numerical models they've been developing for exoplanet atmospheres.

The planet is the closest known 'transiting' planet, and according to the researchers, it is "tidally locked" to its star, just as the moon is tidally locked to the Earth. One of its sides always faces the star while the other side is always dark.

The research team led by Heather Knutson of the Harvard-Smithsonian Center for Astrophysics, Cambridge, Mass., used the Spitzer Space Telescope to measure the infrared light, or heat, as the planet orbited its star.

The findings, the first-ever temperature maps for an exoplanet, revealed that the dayside and nightside temperatures differed only by about 500 degrees Fahrenheit, ranging from 1,200 degrees F on the nightside to 1,700 degrees F on the dayside.

"At these high temperatures, air cools off rapidly when it moves from the dayside to the nightside. That relatively small temperature difference implies that fierce winds redistribute a lot of the heat," said Showman.

"But, we need to do more detailed modelling to calculate actual wind speeds. At this stage, the numbers are all quite uncertain. However, we can be certain the speeds are FAST, probably a couple of kilometres per second, or about 4,500 mph. The supersonic exoplanet winds might be as great as 10 kilometres per second, or about 22,000 mph," he said.

The study, "A map of the day-night contrast of the extrasolar planet HD 189733b," appears in the May 10 issue of the journal Nature.

ANI