A massive planet found orbiting a star at a staggeringly great distance is smashing some long-held theories of planetary formation, researchers say.
The planet, according to a study published online in the Astrophysical Journal Letters, is unlike anything in our solar system.
Eleven times more massive than Jupiter, HD 106906 b orbits a sun-like star at a distance of 96 billion kilometres - about 650 times Earth's distance from our Sun.
"This system is especially fascinating because no model of either planet or star formation fully explains what we see," said study co-author Vanessa Bailey, an astronomy graduate student at the University of Arizona.
Researchers estimate the planet is very young, just 13 million-years-old, and the residual heat from its formation can be seen from Earth as infrared energy. Researchers used infrared cameras and the Magellan telescope in Chile to capture images of the planet. (Until recently, astronomers relied on orbiting spacecraft to capture clear images of exoplanets. Now, Earth-based telescopes employ technology to compensate for atmospheric distortion.)
Astronomers are puzzled by the planet's existence.
Scientists believe that planets that orbit close to stars are formed from the gas, dust and asteroid-like debris that encircle a young star. They believe also that this process is too slow for extremely large planets to form so far from a star.
Authors of the paper speculate that HD 106906 b and its sun might have begun forming at the same time, in the manner that binary stars form. In this case, however, the massive planet never quite became a star.
Binary star systems are formed when two nearby clumps of gas collapse and form separate stars. Because they are so close, they orbit one another.
"It is possible that in the case of the HD 106906 system the star and planet collapsed independently from clumps of gas, but for some reason the planet's progenitor clump was starved for material and never grew large enough to ignite and become a star," Bailey said.
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