Everything you need to know about Kelt-9b - the newly discovered planet that is hotter than most stars

The temperature on Kelt-9b's surface are is more than 4,000C.

Scientists have discovered a planet that’s so hot, it is being vaporised by its own star.

The surface of the planet – called Kelt-9b – is more than 4,000C (7,800 degrees Fahrenheit), which is almost as hot as our Sun.

Here’s everything you need to know about this new incandescent planet:

It is definitely inhabitable.

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With Kelt-9b being hotter than most stars, it is not one where we can aspire to colonise in the distant future.

The planet’s host star – called Kelt-9 – is itself very hot, and the gases in its atmosphere are being blasted with radiation – causing the planet’s atmosphere to “puff up like a balloon”.

Kelt-9b takes just two days to complete one orbit and being so close to its star means the planet is exposed to extreme radiation that is eroding the planet’s atmosphere.

As Keivan Stassun, a physics and astronomy professor at Vanderbilt University, explains: “Kelt-9 radiates so much ultraviolet radiation that it may completely evaporate the planet.”

It is bigger than Jupiter.

Hot planet.
(Robert Hurt/Nasa/JPL-Caltech)

This giant gas planet is 2.8 times more massive than Jupiter, but only half as dense.

In addition, it is tidally locked to its star – just like our Moon is to Earth – which means one side of the planet is always facing toward the star while the other side is in constant darkness.

The Kelt-9 star is only 300 million years old which, scientists say, is quite young in star time.

“Kelt-9 will swell to become a red giant star in a few hundred million years,” Stassun adds. “The long-term prospects for life, or real estate for that matter, on Kelt-9b are not looking good.”

It was spotted last year using Kelt telescopes.

Hot planet.
(Robert Hurt/Nasa/JPL-Caltech)

Kelt-9b was found using one of the two telescopes called Kelt, or Kilodegree Extremely Little Telescope.

Astronomers noticed a tiny drop in the star’s brightness while observing Kelt-9 last year, which suggested a planet may have passed in front of the star.

They also noticed the brightness dipped once every 1.5 days, which the astronomers concluded was due to Kelt-9b’s short orbit.

The research is reported in the journal Nature.


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