CHEOPS observations of WASP-189b in front of and behind its star
CHEOPS observations of WASP-189b in front of and behind its star
CHEOPS measures transit signals from exoplanets with the highest accuracy, i.e. the tiny dip in the star’s light curve when a planet passes in front of the star. This made it possible to measure not only a primary transit event of WASP-189b, i.e. when the planet passes in the line of sight between observer and star (lower measurement curve). CHEOPS could also measure the much smaller secondary signal when the planet disappears behind the star for the observer (upper curve). Extremely precise measurements of such an occultation make it possible to derive the temperature of the planet. It turned out that WASP-189b is about 3200 degrees Celsius, hotter than almost any other exoplanet discovered to date.
