First Hints of Comets Circling Other Stars

By Ron Cowen, Science News May 21, 2010 | 1:40 pm | Categories: Space


A space observatory has taken the first ultrasharp images of rings of cold debris around sunlike stars. The doughnut-shaped rings appear to be extrasolar analogues of the Kuiper belt, the outer solar system’s reservoir of comets and other frozen bodies.

The newly observed rings are either left over from the planet-making process or were generated when planets collided. Astronomers used the European Space Agency’s infrared Herschel Space Observatory, which sports the largest light-collecting mirror in space and is exquisitely sensitive to cold, sand-grain-sized dust, to photograph the belts.

”The Herschel images are the highest resolution far-infrared measurements ever made for debris disks” like the Kuiper belt, says infrared astronomer George Rieke of the University of Arizona in Tucson, who was not involved in the study.


René Liseau of the Chalmers Institute of Technology in Sweden, Carlos Eiroa of the Universidad Autónoma de Madrid in Spain and their colleagues posted their findings on debris belts surrounding two sunlike stars online May 19 and reported evidence of belts around more stars May 20. Some of their findings will also appear in an upcoming Astronomy & Astrophysics.

One of the sunlike stars, called q1Eridani or HD 10647, lies 57 light-years from Earth and has a Jupiter-sized planet orbiting it at about twice Earth’s distance from the sun. The bright ring surrounding the star is a frigid 30 kelvins, lies an average of 85 astronomical units from the star (1 AU is the Earth-sun distance) and is about 40 AU wide. In comparison, the solar system’s Kuiper belt, which lies beyond the orbit of Neptune, resides about 30 to 55 AU from the sun.



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