But inside the bubble, stars would be more likely to have had their disks blown away, the study found.
Our solar system probably formed in a star nursery similar to the Rosette Nebula. But Balog said, "our sun probably didn't get too close to one of these massive stars."
Today our sun's closest star, Proxima Centauri, is nearly 30 trillion miles away.
A Lot of Earths?
"I find it a very optimistic result," said Dimitar Sasselov of the Harvard-Smithsonian Center for Astrophysics in Cambridge, Massachusetts.
"The effect of these massive stars is only important in the near vicinity," he said, so stars outside the zones are still good candidates for planet formation.
But Sasselov and his colleague Scott Kenyon, also at the Center for Astrophysics, think that radiation from an O-star will tend to blow away just gas, and not dust or rocks, from any nearby protoplanetary disks.
This means that the formation of big gas planets similar to Jupiter may be more affected than the formation of smaller, rocky, Earthlike planets inside the zones, they said.
(Related news: "Many 'Earths' Are Out There, Study Says" [April 6, 2005].)
Henry Throop of the Southwest Research Institute at Boulder, Colorado, is skeptical about the new results.
But based on his work on another star-forming region, the Orion Nebula, he agrees that radiation from massive stars could favor the formation of rocky planets.
"We might actually expect to get a lot of Earths in systems like this," Throop said.
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