SCIENCE

This Is The 'Most Eccentric' Planet Yet Known

“It is a fascinating object!”

25/03/2016 5:20 AM AEDT | Updated 29/03/2016 3:04 AM AEDT
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An artist's rendering of the planet HD 20782, the most eccentric planet ever known, passing its star in close orbit.

Astronomers now know more about the universe's "most eccentric" planet than ever before.

The exoplanet, named HD 20782b, is located about 117 light-years away and was first discovered in 2006 -- but a new study, which was released online before print and is slated to be published in The Astrophysical Journal, suggests that it's more extraordinary than previously thought.

The planet not only looks somewhat similar to a comet in appearance, but it also orbits its host star like one too, Dr. Stephen Kane, an astronomer at San Francisco State University and lead author of the study, told The Huffington Post on Thursday. 

"Most planets, including those in our own solar system, have orbits around their star that are shaped like a circle," Kane said. But HD 20782b's lengthy 597-day orbit slingshots it from a far away distance to just close enough to kiss its star.

"This planet is about the size of Jupiter but has an orbit like an ellipse, very similar to what we see for comets. That means that the planet spends most of its time far away from the star, but once per orbit it swings around the star very closely and almost touches the surface," Kane said.

San Francisco State University
The orbit of HD 20782 is shown in red, relative to the inner planets of our own solar system.

The researchers aren't sure how the planet ended up in such a bizarre orbit.

It could possibly have been affected by the gravity of another planet that was once in the star system, Kane offered. Nonetheless, he was shocked when he came across data indicating the planet was in a highly elliptical orbit.

"The notion that a giant planet could exist in such extreme conditions is difficult to imagine," Kane said. "Myself and my collaborators spent several years studying the object further to find out if the situation is as extreme as we initially thought."

Kane and his colleagues noticed that flashes of light would reflect off the planet's atmosphere as it orbited its host star. So, they used a satellite-based telescope to collect that light data, all while timing their observations.

As the researchers detected changes in brightness of the light, they could measure the planet's distance from its star and the shape of its orbit.

"What we found is that, not only is the orbit the most eccentric ever found, the planet shows strong evidence of flashing reflected starlight at us whenever it makes its closest approach to the star," Kane said. "It is a fascinating object!"

Now, the researchers hope to continue their observations in the future to get a closer look at what exactly is happening when HD 20782b makes its closest approach to its star.

"When we see a planet like this that is in an eccentric orbit, it can be really hard to try and explain how it got that way," Kane said in a statement. "We will learn how the planet heats up and cools down again and find out if this process is stripping the atmosphere away from the planet," he told HuffPost.

"Finding more of these kinds of planets," he added, "will hopefully allow us to answer that question."

Correction: A misleading sentence about Earth has been removed from this article.

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