Solar systems like ours may be quite rare
22 Jul 2008, 1443 Hrs

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Washington, July 22 (ANI): A new study has indicated that solar systems like ours may be quite rare.

According to a report in Live Science, as humans look farther into the universe and discover more and more planets beyond the sun, many wonder how typical our own solar system is.

Often astronomers in the planet-hunting business say discoveries of Earth-like worlds are just around the corner.

But a new study indicates our setup may be rare indeed.

A group of astronomers surveyed sun-like stars in the Orion nebula open cluster and found that fewer than 10 percent have enough surrounding dust to make Jupiter-sized planets.

"We think that most stars in the galaxy are formed in dense, Orion-like regions, so this implies that systems like ours may be the exception rather than the rule," said researcher Joshua Eisner, an astrophysicist at the University of California, Berkeley.

That's important because giant planets like Jupiter may be instrumental in fostering life on rocky worlds like Earth.

Eisner and his team observed about 250 stars in the million-year-old Orion Nebula, looking for dense disks of dust surrounding the stars that could be forming planets.

They found that only about 10 percent of the stars emitted radiation in the frequency that would indicate they have these proto-planetary disks of warm dust.

Only 8 percent of the stars surveyed had dust disks with masses greater than one-hundredth the mass of the sun, a mass thought to be the lower limit for formation of Jupiter-sized planets.

These findings seem to agree with what planet hunters are finding so far when they use radial velocity studies to detect extrasolar planets around other stars.

The radial velocity approach involves looking for a wobble in a star's motion caused by the slight gravitational pull of an orbiting planet.

"The current numbers are suggesting 6 to 10 percent of stars have Jupiter-sized planets, which is exactly consistent with our findings," said Eisner.

If it turns out to be true that sun-like stars with Jupiter-sized planets are rare, it may mean that extraterrestrial life is rare as well. (ANI)