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Hottest known planet discovery published in Nature

It’s hot. Seriously hot. Not creeping-into-the-90s-crank-up-the-AC hot: nearly-8,000-degrees-Fahrenheit hot.

KELT-9b is an exoplanet, but its dayside temp beats most stars in our galaxy — and comes close to our sun’s 10,000 degrees. A paper announcing 9b’s discovery, published this week in top science journal Nature, highlights some of the extreme characteristics of both the planet and its host star, KELT-9.

“The big deal about KELT-9b is that it is a planet in a close orbit around a really large and hot host star,” said BYU physics and astronomy research professor and study coauthor Michael Joner. “Everything we will measure about the atmosphere of KELT-9b in the future will represent extreme values and the limits of what is possible for an atmosphere.”

Joner and fellow BYU physics and astronomy professor Denise Stephens are project architects on the Kilodegree Extremely Little Telescope (KELT) survey, spearheaded by researchers at The Ohio State University and Vanderbilt and comprised of more than 20 partner institutions. In the past four years, the group has announced the discovery of 19 exoplanets, and Joner anticipates a few more coming in the next year.

In February the group published a paper on KELT-16b, a so-called “hot Jupiter” recognized for its 4,000-degree heat, size (clocking in at 1.5 times the size of Jupiter) and wonky atmospherics. KELT-9b, said Joner, “is an even more extreme example” than 16b. There’s its hotter-than-any-other-known-planet heat, its size (close to three times the mass of Jupiter), and the massive amount of radiation it receives from a host star that is almost double the temperature of our sun and more than double its size.

“The long-term prospects for life — or real estate, for that matter — on KELT-9b are not looking good,” said Keivan Stassun, a Vanderbilt professor of physics and astronomy and study co-director.

Though the KELT team has been identifying planets whose origins, futures and atmospheres differ dramatically from the earth, Stephens said, understanding the extremes can ultimately help scientists better understand our own planet.

“We really want to find an earth, but the technology is not quite here,” she said. “But everything we learn from the KELT research ties to improving the technology to the point where someday you might be able to image an earth-like object.”

On BYU’s end, Stephens and Joner have worked with a handful of students to help confirm exoplanet candidates identified by the two tiny KELT survey telescopes. Recent grads Kyle Matt and Clement Gaillard are listed as coauthors on the Nature paper, which Matt calls “pretty exciting” — and a nice payoff for many a late night spent tracking the night sky from BYU’s Orson Pratt Observatory. Matt will begin a physics Ph.D. program in the fall, and Gaillard is teaching physics in China.

For Joner, who observes exoplanet candidates from BYU’s West Mountain Observatory, the findings deepen a passion he’s had since childhood. He grew up watching moon landings and dreaming about space exploration, and as a BYU physics student in the late ’70s and early ’80s, remembers talking to his peers about the possibility of other planets outside of our solar system. Since that time, he notes, there have been several thousand planetary discoveries, “expanding the knowledge of what we have around us, the universe we live in and what kinds of things are going on. This is a really golden age.”

Writer: Andrea Christensen

 

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