This video says about itself:
KELT-9b – the hottest giant exoplanet
5 June 2017
650 light years away from Earth, in the constellation Cygnus, astronomers discovered a Jupiter-mass gas giant: KELT-9b. The exoplanet has a dayside temperature estimated around 4300 degrees Celsius. KELT-9b is hotter than most stars and only about 1000 degrees cooler than the Sun.
From Science News:
Scalding hot gas giant breaks heat records
KELT 9b’s temps soar higher than many stars
By Maria Temming
11:00am, June 5, 2017
This Jupiter-like exoplanet revolves around a star just 650 light-years away, locked in an orbit that keeps one side always facing its star. With blistering temps hovering at about 4,300o Celsius, the atmosphere on KELT 9b’s dayside is over 700 degrees hotter than the previous record-holder — and hot enough that atoms cannot bind together to form molecules.
“It’s like a star-planet hybrid,” says Drake Deming, a planetary scientist at the University of Maryland in College Park who was not involved in the research. “A kind of object we’ve never seen before.”
KELT 9b also boasts an unusual orbit, travelling around the poles of its star, rather than the equator, once every 36 hours. And radiation from KELT 9b’s host star is so intense that it blows the planet’s atmosphere out like a comet tail — and may eventually strip it away completely.
The planet is so bizarre that it took scientists nearly three years to convince themselves it was real, says Scott Gaudi of Ohio State University. Deming suspects KELT 9b is “the tip of the iceberg” for an undiscovered population of scalding-hot gas giants.