Star Systems Hint at Possibility of Sun's Nemesis

Star Systems Hint at Possibility of Sun's Nemesis
The left disk is seen face-on. The narrow disk on the right is tipped nearly edge-on from our point of view. The black central circles are produced by the camera's coronagraph, which blocks out the star so its fainter surroundings can be imaged. (Image credit: NASA, ESA, and P. Kalas (University of California, Berkeley))

Debris disks discovered around two nearby stars look strikingly like the Kuiper Belt in the outer part of our solar system, astronomers said today.

The disks were found in a survey of 22 Sun-like stars by the Hubble Space Telescope. By blocking out light from the central stars, Hubble was able to image dust and other material around the stars.

"These are the types of stars around which you would expect to find habitable zones and planets that could develop life," said lead researcher Paul Kalas of the University of California, Berkeley.

Sun's Nemesis?

Kalas and Graham speculate that stars also having sharp outer edges to their debris disks have a companion-a star or brown dwarf-that keeps the disk from spreading outward, similar to how Saturn's moons shape the edges of some of the planet's rings.

"The story of how you make a ring around a planet could be the same as the story of making rings around a star," Kalas said. Perhaps a passing star ripped off the edges of the original planetary disk, but a star-sized companion, remaining in place, would be necessary to keep the remaining disk material from spreading outward, he figures.

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