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article imageRing of star's dust created by trillions of comet collisions

By Andrew Moran     Apr 13, 2012 in Science
Leuven - About 25 light-years away, there is a relatively youthful star named Fomalhaut that is twice the size of our sun and projects a ring of dust around it. Scientists have concluded that the dusty disc is formed by thousands of comet collisions each day.
Fomalhaut, a class A star, is 25 light-years away from us located in the constellation Piscis Austrinus. It was discovered in the 1980s and is believed to be approximately 200 million years old. It is measured to be twice the size of our sun and will exhaust its hydrogen core that it will transform it into a red giant.
Using the Herschel space telescope, astronomers have concluded that the ring dust that surrounds Fomalhaut is due to trillions of comets colliding into the star. The belt of dust is quite distant from the star, though, at more than 100 times the distance from the Earth to the sun and contains temperatures of approximately -200 degrees Celsius (-328 degrees Fahrenheit). Half of the dusty material is water ice.
“This disc is similar to the Kuiper Belt in our Solar System, which lies beyond the planet Neptune, but is much, much younger,” said Dr. Bruce Sibthorpe, researcher at the UK Astronomy Technology Centre, in a press release. “As well as relatively large objects, such as Pluto, our Kuiper Belt also contains millions of much smaller objects.”
The star Fomalhaut and the belt of dust surrounding it  as seen in the far-infrared by the Herschel ...
The star Fomalhaut and the belt of dust surrounding it, as seen in the far-infrared by the Herschel Space Observatory. The ring of dust is created by the collision of thousands of comets every day.
Infrared observations have indicated that the dust is made up of very small grains (few thousandths of a millimetre). Hubble images show, however, that these small grains scatters light similar to its larger counterparts. The colors represented different temperatures; the brighter the parts of the dust are warmer.
Herschel figures suggest that the only way to produce this amount of dust is to have roughly 2,000 kilometre-wide comets collide into the star each day. Dr. Bram Acke, lead study author of Belgium’s University of Leuven, concluded that trillions of comets have come into contact with Fomalhaut, which, he notes, has enough material to establish 100 Earths.
“I was really surprised. To me this was an extremely large number,” stated Dr. Acke.
More about Fomalhaut, ring of dust, Comets, Collisions, astronomers herschel
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