In fact it is so hot, dayside temperatures measure more than 7,800 degrees Fahrenheit, that experts say it calls into question the entire definition of what constitutes a planet.
The new space object, KELT-9b, is nearly twice as hot as our sun and is so warm that it is being vaporized by it’s own star – KELT-9, which is even hotter.
Scott Gaudi, astronomy professor at the Ohio State University, and lead author, said: “This is the hottest gas giant planet that has ever been discovered,”
“It’s a planet by any of the typical definitions of mass, but its atmosphere is almost certainly unlike any other planet we’ve ever seen just because of the temperature of its dayside.”
KELT-9b is measured at 2.8 times bigger than Jupiter, which is unusual, but scientists speculate the extreme ultraviolet radiation given off by its host star has caused the planet’s atmosphere to puff up “like a balloon”.
In fact there is so much ultraviolet radiation bombarding the surface of the 300-million-year-old planet, that molecules such as water, carbon dioxide and methane can’t form.
But the long-term prospects for this unique planet are less impressive.
Professor Keivan Stassun said: “KELT-9 will smell to become a red giant star in a few hundred million years...the long-term prospects for life, or real estate for that matter, on KELT-9b are not looking good.”
But looking too far into the future might not be necessary as one ‘year’ on KELT-9b is the equivalent of two days on Earth.
The planet is also unusual in that it orbits perpendicular to the spin axis of the star. That would be analogous to the planet orbiting perpendicular to the plane of our solar system.
The astronomers hope to take a closer look at KELT-9b with other telescopes ― including NASA’s Spitzer and Hubble space telescopes.
Observations with Hubble would enable them to see if the planet does have a cometary tail, and determine how much longer that planet will survive its current hellish conditions.