KELT-9b hot planet

Life as we know it isn’t happening on KELT-9b. The tidally locked planet is a scorcher with day side temperatures hitting 4,600 Kelvin (that’s more than 7,800 degrees Fahrenheit). That makes this exoplanet hotter than many stars, and just 2,000 degrees Fahrenheit cooler than our own sun.

The extreme temperatures mean molecules forming the basic building blocks of life such as water, carbon dioxide and methane can’t even form on the day side. Researchers aren’t sure about the night side, though. But any molecules that do form probably wouldn’t last long.

“It’s a planet by any of the typical definitions on mass, but its atmosphere is almost certainly unlike any other planet we’ve ever seen just because of the temperatures of its day side,” says Scott Gaudi, professor of astronomy at Ohio State University and a leader of the study.

As you can tell by the temperatures, KELT-9b hangs out way too close to its star (KELT-9). The gas giant 2.8 times more massive than Jupiter circles its star once every 36 hours. While the Jupiter-like world is more massive, it’s actually less dense according to the team of researchers.

Huge amounts of ultraviolet radiation from KELT-9 slam into the gas giant’s atmosphere causing it to expand like a balloon and bleed atmosphere into space. The radiation bombardment may even form a tail of planetary stuff behind it. Almost like a comet, according to Gaudi. The concept video shows KELT-9b with a tail streaking behind it.

KELT-9b’s future isn’t looking good

There are two likely outcomes for KELT-9b. Neither leaves the planet unscathed. The radiation from KELT-9 could evaporate the planet completely. There are theories suggesting gas giants have rocky cores. In that case, KELT-9b would turn into a much smaller, rocky world.

The other scenario is all bad news for KELT-9b. If the radiation doesn’t do it in first, the star swelling to become a red giant will do the trick. Remember, KELT-9b is already orbiting incredibly close to its star. Once KELT-9 becomes a red giant (in about a billion years), it’ll swallow KELT-9b.

Either way, don’t expect NASA to make any fancy travel brochures for this hot world.

Besides showing us a glimpse of the extremes in the universe, why even search for a world like this? Keivan Stassun, a professor of physics and astronomy at Vanderbilt who assisted Gaudi with the study, explains why:

“As we seek to develop a complete picture of the variety of other worlds out there, it’s important to know not only how planets form and evolve, but also when and under what conditions they are destroyed.”

A bargain-bin telescope

For this kind of astronomy at least. Your average telescope sitting on the peak of Mauna Kea, Hawaii or floating in space costs millions of dollars to build and operate. But the KELT-North telescope at Winer Observatory in Arizona gives researchers the ability to study worlds hundreds of light-years away for a fraction of that cost.

Two KELT telescopes are operated by astronomers at Ohio State, Vanderbilt University and Lehigh University. Each one costs less than $75,000. The telescopes use off-the-shelf technology instead of custom-built mirrors.

Instead of studying very faint stars in a tiny part of the sky. KELT specifically goes after bright stars and can look at millions of them at once at low resolution.

Joshua Pepper, an assistant professor of physics at Lehigh University and builder of the two KELT telescopes, cheered the smaller telescopes. “This discovery is a testament to the discovery power of small telescopes, and the ability of citizen scientists to directly contribute to cutting-edge scientific research.”

Plus, being able to sweep across large portions of the sky at once leads to more and quicker discoveries. Other telescopes like Hubble and the upcoming James Webb Space Telescope can then take a closer look.

Stassun and Gaudi hope to get some time with the Hubble Space Telescope and see if KELT-9b does indeed have a comet-like tail. And get a better idea at just how long the gas giant can last in its extreme environment.


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