The vast disk of debris encircling Fomalhaut B hosts a rogue planet which may unleash a cataclysm in 2032.
Newly-released Hubble images show that the debris belt is wider than previously known, spanning a section of space from 14 to nearly 20 billion miles from the star.
Even more surprisingly, though, they reveal that the planet, Fomalhaut b, follows an unusual elliptical orbit that carries it on a potentially destructive path. The 2,000-year-long orbit swings as close to the star as 4.6 billion miles, and as far away as 27 billion miles.
“We are shocked. This is not what we expected,” says Paul Kalas of the University of California at Berkeley and the SETI Institute.
The team now believes that there may be other planet-like bodies in the system that gravitationally disturbed Fomalhaut b to place it in such a highly eccentric orbit.
“Hot Jupiters get tossed through scattering events, where one planet goes in and one gets thrown out,” says Mark Clampin of NASA’s Goddard Space Flight Center. “This could be the planet that gets thrown out.”
If its orbit lies in the same plane as the dust belt, says the team, then Fomalhaut b will intersect the belt around 2032 on the outbound leg of its orbit – potentially causing quite some fireworks. Most, though, will only be visible in infrared light. And if Fomalhaut b isn’t in the same plane as the belt, all that will be seen is a gradual dimming of the planet as it travels farther from the star.
Fomalhaut, says the team, looks a lot like our own, some four billion years ago. The planetary architecture is being redrawn, the comet belts are evolving, and planets may be gaining and losing their moons.