5,400mph winds discovered on Hot Jupiter exoplanet

Astrophysicists from the University of Warwick have discovered a Hot Jupiter-type exoplanet where the winds travel at 5,400mph – more than two kilometers per second, and 20 times stronger than the fastest winds ever recorded on Earth, according to a new study.

The planet, HD 189733b, is the first world beyond the solar system to have its weather directly mapped and measured, explained lead author Tom Louden and his colleagues in the latest issue of Astrophysical Journal Letters. While studying the planet, they found winds moving from the day side of the planet to its night side at a velocity seven times the speed of sound.

“This is the first ever weather map from outside of our solar system,” Louden, a Ph.D. student at the university, said in a statement. “Whilst we have previously known of wind on exoplanets, we have never before been able to directly measure and map a weather system.”

New technique used to map the distant planet’s weather system

Louden and co-author Dr. Peter Wheatley measured the object’s velocity by using high resolution spectroscopy of sodium absorption occurring in its atmosphere. As portions of HD 189733b’s atmosphere moved towards or away from Earth, this wavelength of this feature is altered by the Doppler effect, enabling measurements of its speed.

“The surface of the planet’s star is brighter at the center than it is at the edge, so as the planet moves in front of the star the relative amount of light blocked by different parts of the atmosphere changes,” Loudon said. “For the first time we’ve used this information to measure the velocities on opposite sides of the planet independently, which gives us our velocity map.”

The study authors used the High Accuracy Radial velocity Planet Searcher (HARPS) in La Silla, Chile, to collect data on HD 189733b. The planet is approximately 10 percent bigger than Jupiter and 180 times closer to its star, giving it a surface temperature of roughly 1,200 degrees Celsius. Its relative closeness to our solar system has made it a popular research subject.

“We are tremendously excited to have found a way to map weather systems on distant planets,” Dr. Wheatley added. “As we develop the technique further we will be able to study wind flows in increasing detail and make weather maps of smaller planets. Ultimately this technique will allow us to image the weather systems on Earth-like planets.”

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Image credit: Mark A. Garlick/University of Warwick

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