Second Asteroid Ring Found In Three-Star Planetary System
Dec 28, 2013 11:39 AM EST
The planetary system around the star Fomalhaut A is the most well-known other than our own; a new study found that the three-star system harbors an intriguing comet belt.
Fomalhaut A is one of the brightest stars visible from our planet, and its solar system contains an "exoplanet and a spectacular ring of comets," a Royal Astronomical Society (RAS) new release reported. The new discovery found another comet belt near the close-by stat Fomalhaut C.
The star is a "white-blue" color and is located 25 light years away in the constellation Piscis Austrinus.
The Hubble Telescope first spotted the comets, and a planet called Fomalhaut b (orbiting the star Fomalhaut B) back in 2008.
"It's very rare to find two comet belts in one system, and with the two stars 2.5 light years apart this is one of the most widely separated star systems we know of. It made us wonder why both Fomalhaut A and C have comet belts, and whether the belts are related in some way," lead author Grant Kennedy, an astronomer at the Institute of Astronomy at the University of Cambridge, said.
The researchers hope this discovery could help researchers solve a mystery of the Fomalhaut A planetary system that has had them scratching their heads for ages.
The orbit around the comets and Fomalhaut a are elliptical, researchers have suggested this could be due to a "close encounter" with a nearby orbit.
"The discovery of the comet belt around C is important because such encounters can not only make the comet belts elliptical, they can also make them brighter by causing the comets to collide more often, releasing massive amounts of dust and ice," the news release reported.
Such a bright comet belt orbiting a star is extremely rare, this suggests the region may have been subjected to previous close encounters.
"We thought that the Fomalhaut A system was disturbed by a planet on the inside -- but now it looks like a small star from the outside could also influence the system. A good test of this hypothesis is to measure the red dwarf's exact orbit over the next few years," Paul Kalas of the University of California said.
The phenomenon can be compared to comet ISON, which got too close to our Sun and disintegrated in November.
"Over the last few years we used Herschel to look for comet belts around many stars within a few hundred light years of the Sun. At that stage Fomalhaut C was just called LP 876-10 and we thought it was a lone red dwarf with a comet belt. It was interesting because such discoveries are very rare, but didn't tell us why it was there. After the discovery that this star was part of the Fomalhaut system, the existence of its comet belt made us think harder about connections between the two stars, and it may be that it helps solve the mystery of the elliptical comet belt around Fomalhaut A," Kennedy said.