for National Geographic News
It's more likely than ever that we are not alone in the universe, new research suggests.
The latest computer models are telling scientists that more than a third of the star systems containing Jupiterlike gas giants may also harbor Earthlike planets.
These so-called habitable exoplanets could be awash in oceans of liquid water, which means they might support life (related news: "Are Neighborhood Aliens Listening to Earth Radio?" [September 7, 2006]).
The latest work focuses on a type of star system that contains gas giants known as hot Jupiters.
Unlike gas giants in our solar system, hot Jupiters have orbits that swing tightly around their stars, says Sean Raymond, study co-author and astrophysicist at the University of Colorado in Boulder.
Scientists believe that hot Jupiters initially form far from their host stars. Over time the gas giants migrate inward due to the irregular twisting motions of the gaseous disks in which they formed.
As they move into their near-star orbits, hot Jupiters could be playing violent games of planetary billiards that produce Earthlike planets, he says.
In general, massive gas giants have a reputation for slinging things around in space.
Our Jupiter (Hubble image) is capable of hurling asteroids out of the solar system or into the sun and other planets by the sheer force of its gravity.
"These gas giants cause quite a ruckus," Raymond said.
Ten years ago, when scientists detected the first hot Jupiter, they assumed that as the giant exoplanets plowed through debris during their inward migrations, any surrounding material would be similarly ejected.
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