WASP 189

Getting broiled is an understatement for the Wasp 189 system.

WASP-189b, the target of the CHEOPS observations, is an exoplanet orbiting the star HD 133112, one of the hottest stars known to have a planetary system. "The WASP-189 system is 322 light years away and located in the constellation Libra (the weighing scales)," explains Monika Lendl, lead author of the study from the University of Geneva, and member of the National Center of Competence in Research PlanetS.

"WASP-189b is especially interesting because it is a gas giant that orbits very close to its host star. It takes less than three days for it to circle its star, and it is 20 times closer to the star than Earth is to the Sun," Monika Lendl says. The planet is more than 1.5 times as large as Jupiter, the largest planet of the solar system.

Which means ...

Monika Lendl further explains that planetary objects like WASP-189b are very exotic: "They have a permanent day side, which is always exposed to the light of the star, and, accordingly, a permanent night side." This means that its climate is completely different from that of the gas giants Jupiter and Saturn in our solar system. "Based on the observations using CHEOPS, we estimate the temperature of WASP-189b to be 3,200 degrees Celsius. Planets like WASP-189b are called "ultra-hot Jupiters. Iron melts at such a high temperature, and even becomes gaseous. This object is one of the most extreme planets we know so far," says Lendl.

How CHEOPS finds these outliers.

When a planet passes in front of its star as seen from Earth, the star seems fainter for a short time. This phenomenon is called a transit. When the planet passes behind the star, the light emitted and/or reflected by the planet is obscured by the star for a short time. This phenomenon is called occultation. Credit: © ESA

We know so little but at least we're trying. :)