A closeup of the star HD 106906 and its surroundings revealed a planetary system that was recently disturbed by gravitational turbulence. Photo by Paul Kalas/UC Berkeley
BERKELEY, Calif., Dec. 1 (UPI) -- New research by an international team of astronomers suggests a misunderstood exoplanet was likely expelled from its inner orbit. The revelation offers scientists a clearer vision of the chaos found in young planetary systems.
The star HD 106906, a younger version of our sun, is located 300 light years away near the constellation Crux. Exoplanet HD 106906 b circles at at unusually large distance, separated from its host star by 650 astronomical units.
An astronomical unit, or AU, is the average distance between the sun and Earth -- roughly 93 million miles.
Not only is HD 106906 b really far away, it is also quite large, 11 times the size of Jupiter. For some time, astronomers have been trying to come up with an explanation for how such a large planet formed so far away from its sun.
The new analysis, however, shows the alien world was likely expelled from a more intimate position by gravitational turbulence -- caused either by a passing star or conflict with another large world.
Astronomers came to this realization after more closely imaging the planet and its surroundings. Observations revealed a dusty ring of debris, similar in size to the solar system's Kuiper Belt, surrounding the star.
But the ring, which hosts comet dust, extends farther out than expected and is lopsided, thicker on the side farthest from the exoplanet of note.
"These discoveries suggest that the entire planetary system has been recently jostled by an unknown perturbation to its current asymmetric state," Paul Kalas, an adjunct professor of astronomy at the University of California, Berkeley, said in a press release. "The planet is also unusual in that its orbit is possibly tilted 21 degrees away from the plane of the inner planetary system, whereas most planets typically lie close to a common plane."
The imaging work of Kalas and his colleagues, aided by the Hubble Space Telescope, also revealed a ring of debris around the exoplanet, suggesting HD 106906 b may have picked up some rubble on its trip to the outer reaches of its solar system.
The story of planetary exile was recently detailed in the Astrophysical Journal, but the study's authors say there are other potential explanations for the planet's unusual position and the lopsided ring of rocks.
Still, the unusual solar systems holds promise as a vehicle to better understand how our solar system may have once kicked out planets.