Sinister Security: KELT-11b

Astronomer Discovered a ‘Styrofoam’ Exoplanet That Could Float On Water

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KELT-11b is one of the brightest transiting exoplanets in the southern hemisphere. It’s one fifth the size of Jupiter, but is most famous for it’s ‘inflated atmosphere’ that is often described as similar to styrofoam. It’s entirely possible that KELT-11b (a true gas giant) could float on water.

The planet was discovered during the KELT (Kilodegree Extremely Little Telescope) survey. In order to locate the object, two telescopes (one in South Africa and one in Arizona) work together to find transiting objects.

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A transit or astronomical transit is the phenomenon of at least one celestial body appearing to move across the face of another celestial body, hiding a small part of it, as seen by an observer at some particular vantage point.

“The KELT project is specifically designed to discover a few scientifically valuable planets orbiting very bright stars, and KELT-11b is a prime example of that. We were very surprised by the amazingly low density of this planet. It’s extremely big for its mass. It’s got a fifth of the mass of Jupiter but is puffed up into this really underdense planet.”– Joshua Pepper, Lehigh University

KELT’s inflated atmosphere is 1,700 miles or 2,760 kilometers across. It’s 320 light-years from Earth and is so close to it’s parent star that it completes an orbit every 5 days. KELT-11b has the third lowest density of any accurately measured exoplanet.

This is an artist’s rendering of KELT-11b, a ‘styrofoam’-density exoplanet orbiting a bright star in the southern hemisphere. (Walter Robinson/Lehigh University)

“We don’t know of any real Earth-like planets or stars for which we can measure their atmospheres, though we expect to discover more in future years. These (giant gas) planets are the gold standards or testbeds for learning how to measure the atmospheres of planets.” adds Joshua Pepper.

Astronomers are trying to figure out the cause for KELT-11b’s inflation and further study is needed to analyze the data. The planet’s large atmosphere can also provide a mechanism for testing hability products in new and uncharted atmospheres.

We’ll need new tools to analyze the atmosphere of planet’s such as KELT; there’s a big hope that the upcoming launch of the James Webb Space Telescope can provide answers to questions like these.

Source: Astrophysical Journal/EurekaAlert

Scientists Have Discovered a 'Puffy' Exoplanet With The Density of Styrofoam

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Astronomers have found a giant exoplanet larger than Jupiter, but with extremely low mass - a composition that gives this mysterious 'puffy planet' a density very similar to styrofoam.

The team who found KELT-11b, which orbits a star located about 320 light-years from Earth, says this "extraordinarily inflated" world is the third-lowest density planet with a precisely measured mass and radius that has been discovered – and this oddball, lightweight sphere could tell us more about how such strange exoplanets evolve.

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"It is highly inflated, so that while it's only a fifth as massive as Jupiter, it is nearly 40 percent larger, making it about as dense as styrofoam, with an extraordinarily large atmosphere," says astronomer Joshua Pepper from Lehigh University in Pennsylvania.

Apart from KELT-11b's unusual density, one of the things that makes the exoplanet stand out is its host star's extreme brightness. The star, called KELT-11, is in the process of evolving into a red giant, meaning it's started using up its nuclear fuel, fusing hydrogen in a shell outside its core.

Scientists now predict that sometime within the next 100 million years, KELT-11b will end up being engulfed by its host star, as KELT-11's outer layers expand to consume the styrofoam-like world.

That engulfment won't take long, either, since the planet hangs very close to its host, orbiting KELT-11 in less than five days. But before that engulfment happens, the puffy planet stands to teach scientists more about its atmospheric makeup, thanks to the intense brightness generated by KELT-11.

The star is in fact the brightest visible star in the Southern Hemisphere that's known to host a transiting planet – referring to how KELT-11b passes in between the star and Earth during its orbit.

That transit is how astronomers often detect exoplanets, as the amount of light space telescopes receive from these distant stars dips slightly as the exoplanet passes in front of them. But in the case of KELT-11, the sub-giant's intense luminosity meant that the dip in light caused by KELT-11b's transit was barely recognisable to astronomers using the KELT (Kilodegree Extremely Little Telescope) survey – a pair of robotic telescopes located in Arizona and South Africa.

"This discovery was very challenging. The original KELT observations of the star – its light curve – showed only a hint of the transit. Because the transit is both shallow (a little under 0.3 percent change in brightness) and long, it was very difficult to obtain reliable, complete confirmation observations." Pepper told Tomasz Nowakowski at Phys.org last year, when the team first announced their findings prior to peer-review.

Follow-up observations eventually confirmed the existence of KELT-11b, and now the same extreme backlight that made its initial discovery so difficult could help the team figure out the composition of its atmosphere. And that could provide clues on how this styrofoam world got so unusually inflated.

As it stands, KELT-11b is about twice as large as the scientists can explain, given its mass and proximity to its host, but now that we know it's there, it's a great opportunity to find out more about these styrofoam-like planets, and what makes them so big but so sparse at the same time.

"We think that KELT-11b will be a great test case to help us understand the mechanism that causes inflated planets. Furthermore, since the host star has evolved onto the sub-giant branch and is reaching the end of its life, we hope that we can study the behaviour of planetary systems at the end-stage of their star's lifetime." Pepper told Phys.org.

The findings are reported in The Astronomical Journal.

Sinister Security

Astronomer Discovered a ‘Styrofoam’ Exoplanet That Could Float On Water

Scientists Have Discovered a 'Puffy' Exoplanet With The Density of Styrofoam

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