Rogue Planet Orbit Spotted by NASA's Hubble


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New images of the Fomalhaut star system could show evidence of a "titanic planetary disruption." Astronomers have found that the debris belt in the system is wider than was thought, and that a "rogue" planet has a precarious orbit that takes it straight through the dust ring. The debris belt spans a huge section of space from 14 to around 20 billion miles from Fomalhaut. The planet, Fomalhaut b, comes as close as 4.6 billion miles from its star before swinging out 27 billion miles away from it.

"We are shocked. This is not what we expected," said Paul Kalas of the University of California at Berkeley and the SETI Institute in Mountain View, Calif.

Kalas led a team that recalculated Fomalhaut b's orbit from newer observations made last year using NASA's Hubble Space Telescope. He and his colleagues say these new findings suggest that there could be other objects in the system that sent the planet on its wild trajectory. Hypotheses include an undiscovered planet that gravitationally ejected Fomalhaut b, or a dwarf planet that collided with it.

"Hot Jupiters get tossed through scattering events, where one planet goes in and one gets thrown out," said Mark Clampin of NASA's Goddard Space Flight Center. "This could be the planet that gets thrown out."

If Fomalhaut b is in the same plane as the dust belt, it will enter the debris around 2032. Astronomers have also detected irregularities and gaps across the dust belt, suggesting that there are other planets to search for in the Fomalhaut system.