Picture: ISTOCK
Picture: ISTOCK

A planet with the density of Styrofoam has been discovered by researchers at the South African Astronomical Observatory in Sutherland.

The exoplanet‚ dubbed Kelt-11b after the telescopes that found it‚ orbits a star 320 light years away and is a gas giant similar to Jupiter and Saturn.

But it hugs its host star‚ Kelt-11‚ so closely that it completes an orbit in less than five days. And‚ while it has only a fifth of Jupiter’s mass‚ it is 40% larger in radius.

"This means that this new bloated planet has about the same density as Styrofoam‚" an observatory spokesperson said on Thursday after the publication of the researcher’s findings in The Astronomical Journal.

"This puffed-up planet also has a very large atmosphere‚ providing researchers the opportunity to study its atmospheric properties in detail. These studies will be useful for developing tools to assess earth-like planets for signs of life in future."

The Kelt (Kilodegree Extremely Little Telescope) project consists of two small‚ robotic telescopes‚ one in Sutherland and the other in Arizona in the US.

"The exoplanet was first discovered with the [Sutherland] telescope and thereafter monitored by many telescopes around the world operated by researchers at universities as well as telescopes operated by amateur astronomers‚" the observatory said.

"The KELT telescopes scan the sky every night‚ measuring the brightness of about 5-million stars. Astronomers search for stars that seem to dim slightly at regular intervals‚ which can indicate a planet is orbiting that star and eclipsing it.

"Much larger telescopes are then used to measure the gravitational ‘wobble’ of the star — the slight tug a planet exerts on the star as it orbits — to verify that the dimming is due to a planet‚ and to measure the planet’s mass."

Said observatory astronomer Rudi Kuhn‚ who helped to build the Sutherland telescope: "This is a very exciting discovery. The planet KELT-11b orbits one of the brightest stars known to host an exoplanet and is one of the most inflated planets ever discovered.

"This enables us to make some very detailed observations of the atmospheric composition of the exoplanet using much larger telescopes‚ like the Southern African Large Telescope (Salt).

"This will help us understand how these giant planets are formed‚ why they have such small orbits as well as what might happen to them in the future."

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