Meet the planet that's hotter than most stars

A 300-million-year-old planet discovered in 2014has a temperature that can reach a scorching 4,315 C during the day, just 926 C cooler than our sun, astronomers have found.

The young planet,KELT-9b, is about 650 light-years away and is 2.8 times more massive than Jupiter, but only half as dense.

The planet's intense heat comes from its star, KELT-9, that is more than twice as large as our sun and nearly twice as hot.

"KELT-9 radiates so much ultraviolet radiation that it may completely evaporate the planet,"Keivan Stassun, a professor of physics and astronomy at Vanderbilt University who took part in the study published in the journal Nature, said in a statement. "Or, if gas giant planets like KELT-9b possess solid rocky cores as some theories suggest, the planet may be boiled down to a barren rock, like Mercury."

KELT9bis tidally locked to its host star, in the same way the moon is tidally locked with Earth one side is always facing KELT-9. Because of this, molecules like water, methane, carbon dioxide and hydrogen are unable to form.

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As the star produces such intense radiation, the day side of planet's atmosphere would be stripped down to individual atoms.

"Then as night falls, all those hydrogen atoms will try and get back together, creating an inferno at dusk," said ThomasBeatty, a research scientist at Penn State University and a co-author on the study. "On Earth, this same process is used to create one of the hottest welding flames known."

As the intense UV blasts the planet, it could be throwing some of the evaporated material into space as the planet orbits, sort of like a comet, the researchers said.

In about a million years, the star will swell and become a red giant, which would consume the planet if it is still around. It's just what our sun will do to Earth in about 5.4 billion years.