This exoplanet experiences supersonic winds at 33,000 km/h!

At 520 light years from us, WASP-127b is not a planet that we can call habitable. It is gaseous, very hot, of remarkably low density and has an equatorial jet current blowing at around 33,000 km/h! This is a universal record in this area: no wind in the Solar System or any other exoplanet has ever been measured so fierce. For comparison, the Great Red Spot on Jupiter swirls at 600 km/h and Neptune's winds, although known as the fastest in our immediate vicinity, do not exceed 2100 km/h.

One side perpetually lit at 1130°C, the other plunged into eternal frozen night

This gaseous exoplanet is 30% larger than Jupiter, but weighs five times less. It is even one of the least dense planets known, a real cotton candy. It orbits in just 4 days and 4 hours around a yellow G-type star, exactly like our Sun.

However, such a tight orbit requires being very close to its star, so it is very likely that WASP-127b is locked by the latter's gravity. The exoplanet always shows the same face, like the Moon with the Earth, thus completing its rotation and its revolution at the same time. From then on, one of its faces is always extremely hot, the other much colder. On the eternal day side, the temperature was estimated in this scientific publication at 1400 K, or around 1130 °C, according to measurements by NASA's Spitzer space telescope. The perpetual night side could drop by 1000°C, or even more.

A cooler temperature at sunrise

It is therefore by using the Very Large Telescope in Chile of the ESO (European Southern Observatory) and its CRIRES instrument that astronomers were able to measure the speed of its winds. And they noticed several very interesting things… First, this current forced at the equator flows at more than 9 km/s (33,000 km/h), while the temperature of the planet is colder at the terminator (line which separates the illuminated and unilluminated faces) in the morning than in the evening.

The poles being much cooler than the rest of the planet, we must imagine these extreme winds as burning! “Understanding the dynamics of these exoplanets allows us to explore mechanisms such as heat redistribution and chemical processesexplains David Cont of the Ludwig Maximilian University of Munich, co-author of the article. This improves our understanding of planet formation and could shed light on the origins of our own solar system.”

The authors of the astronomical study were also able to analyze the composition of the atmosphere and found water (H²O) and carbon monoxide (CO).

Last interesting point, the ESO notes in its press release that this type of measurements cannot currently be carried out from space telescopes such as the James-Webb, because they do not have the precision necessary to measure speeds. L'ESO's Extremely Large Telescopecurrently being built near the VLT, will allow researchers to even better study the weather conditions of exoplanets.

“This means we will likely be able to resolve even finer details of wind patterns and extend this research to smaller, rocky planets.”concludes Lis Nortmann, first author of the article.