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7 June 2017

Newly Discovered Planet is Hotter than Most Stars

With an average surface temperature of 462°C (864°F), Venus is the hottest planet in our solar system. Such heat would quickly melt even fairly robust elements such and lead and zinc, but this is nothing in comparison to the newly discovered exoplanet KELT-9b, where temperatures climb as high as 4,326°C (7,818°F). To put that into context, the Sun has an approximate temperature only slightly higher, relatively speaking of course, at 5,600°C (10,000°F).

KELT-9b’s own local star however, known as KELT-9, is much younger, larger, and hotter than our own; in fact, the star is so hot that is may be evaporating the aforementioned exoplanet, which is comprised largely of gas.

“This is the hottest gas giant planet that has ever been discovered,” said Scott Gaudi, astronomy professor at The Ohio State University in Columbus, who led a study on the topic.

The extreme temperature of KELT-9b comes not only from the heat of its local star, but also the fact that the planet is tidally locked to it. This means that one side of the planet is constantly facing the star, and receiving the overload of heat and radiation that comes as a result. The UV radiation is so abundant that molecules such as water, carbon dioxide, and methane can’t even form on the daylight-drenched side of the planet.

The extreme radiation has another effect on the planet; KELT-9b is 2.8 times more massive than Jupiter, but only half as dense. Scientists would expect the planet to have a smaller radius, but the radiation pumped out by its local star has caused the planet’s atmosphere to swell, thereby increasing its size.

“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,” Gaudi remarked.

Not only is the atmosphere of the planet swelling, it may in fact be evaporating, leaving a tail in its wake much like a comet. Such conditions may cause the planet to evaporate entirely, if the star doesn’t engulf the planet and wipe it out in dramatic fashion before that can happen.

“KELT-9 will swell to become a red giant star in a few hundred million years,” said Keivan Stassun, a professor of physics and astronomy at Vanderbilt University, Nashville, Tennessee, who directed the study with Gaudi. “The long-term prospects for life, or real estate for that matter, on KELT-9b are not looking good.”

Sam Bonson

Sam is an aspiring novelist with a passion for fantasy and crime thrillers. He is currently working as a content writer, journalist & editor in an attempt to expand his horizons.