Which exoplanet is one of the hottest known?

KELT-9b is often described as one of the hottest exoplanets ever discovered. Orbiting a hot A-type star every 1.5 days, it receives intense radiation that drives dayside temperatures to roughly 4,000°C or more. At those temperatures, even molecules cannot survive easily, and metal species can be detected in vapor form. Its extreme environment gives astronomers a rare look at atmospheric chemistry under conditions far beyond anything in the Solar System.