Planet eleven times the size of Jupiter astounds astronomers

Dec. 6 (UPI) -- Exoplanet HD 106906 b is the furthest-orbiting planet from its star, 11 times the size of Jupiter, and could actually be a failed star.

The planet, which is 11 times the size of Jupiter, is orbiting a star at 650 times the average Earth-Sun distance. University of Arizona researcher Vanessa Bailey said the planet and star system are like none they have ever seen before.

"This system is especially fascinating because no model of either planet or star formation fully explains what we see," said Bailey.

Astronomers estimate the planet is just 13 million years old, compared to Earth's 4.5 billion years. The planet, still resonating heat, is around 2,700 °F and is much cooler than its host star.

The accepted theory with planets orbiting close to a star is that they are formed from gas, dust and asteroid-like debris that circle a young star. This process is also a slow one , which is why scientists aren't sure if this is how HD 106906 b was formed, given its relatively young age.

Another theory is that the planet could have been formed at the same time as the star and could be part of a binary system. In this case HD 106906 b never grew to become a star, possibly because it was starved for material and never grew large enough to ignite.

“Systems like this one, where we have additional information about the environment in which the planet resides, have the potential to help us disentangle the various formation models,” Bailey said. "Future observations of the planet's orbital motion and the primary star's debris disk may help answer that question."

[University of Arizona]