Washington: Astronomers have discovered that the least massive star of the Fomalhaut system, Fomalhaut C, hosts its own comet belt.
Fomalhaut A is one of the brightest stars in the sky. Located 25 light-years away in the constellation of Piscis Austrinus, it shines with a blue-white color and is prominent from the southern hemisphere.
Fomalhaut A`s prominence made it a key target for the Hubble Space Telescope, which astronomers used to find the ring of comets, hints of and then a direct image of the planet, Fomalhaut b, in 2008 (astronomers use uppercase letters for stars, and lowercase letters are used for planets, so `Fomalhaut b` is a planet, and `Fomalhaut B` is the second star in the system).
Lead author Grant Kennedy, an astronomer at the Institute of Astronomy at the University of Cambridge, said 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 they know of, which made them wonder why both Fomalhaut A and C have comet belts, and whether the belts are related in some way.
This discovery may help solve the major mystery in the Fomalhaut system: the orbits of the comet ring and planet around Fomalhaut A are elliptical (which simply means that the orbits aren`t circular). The elliptical orbits are thought to be the result of close encounters with something else in the system, perhaps with another as yet undetected planet or perhaps with one of the two other stars, B or C.
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 research has been published in a letter to the journal Monthly Notices of the Royal Astronomical Society.