Astronomers Using Hubble Find Evidence of Planet Forming 7.5 Billion Miles Away From Its Star

Posted on June 14, 2013

Astronomers using NASA's Hubble Space Telescope have found evidence of a planet forming 7.5 billion miles away from its star. In a NASA news release, astronomers say the finding may challenge current planet formation theories. The suspected exoplanet is also the first to be found so far away from its star. The planet is orbiting TW Hydrae, a red dwarf located 176 light-years from Earth in the constellation Hydra. The image above shows the protoplanetary disk of dust and gas around TW Hydrae. You can find a larger version of the image here.

The suspected planet is about 6 to 28 times as massive as Earth. It is about the twice the distance from its sun as Pluto is from our sun.

The astronomers also note that the suspected planet appears to have formed much quickly than the current theory of planet formation allows. The current theory predicts a slow buildup over tens of millions of years. The astronomers say a planet 7.5 billion miles from its star should take over 200 times longer to form than Jupiter did, which took about 10 milion years. TW Hydrae is only 8 million years old, so there would not have been nearly enough time for the planet to form under the current theory.

John Debes of the Space Telescope Science Institute in Baltimore, Md., says, "It's so intriguing to see a system like this. This is the lowest-mass star for which we've observed a gap so far out."

The release says there is an alternative planet formation theory that suggest a planet could form more rapidly if a piece of the disc becomes gravitationally unstable and collapses on itself. A planet could form in just a few thousand years in this scenario. The release does not discuss the possibility the suspected planet is a rogue planet, so presumably they have ruled out that scenario.

A research paper about the planet was published in The Astrophysical Journal.

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