Thursday, July 27, 2006
The steady discovery of giant planets orbiting stars other than our sun has heightened speculation that there could be Earth-type worlds in nearby planetary systems capable of sustaining life. Now researchers running computer simulations for four nearby systems that contain giant planets about the size of Jupiter have found one that could have formed an Earth-like planet with the right conditions to support life.
A second system is likely to have a belt of rocky bodies the size of Mars or smaller. The other two, the models show, do not have the proper conditions to form an Earth-size planet. Each system lies within 250 light years of Earth (a light year is about 5.88 trillion miles). Astronomers already have found evidence that each system contains at least two giant planets about the mass of Jupiter, which have migrated close to their stars, perhaps as close as Mercury is to the sun.
For each of the four systems, the researchers conducted 10 computerized simulations that placed small planet embryos, or protoplanets, in the system to see if they are able to gather more material and form a true planet the size of Earth. Each simulation assumed the same conditions in the planetary system except that the position and mass of each protoplanet was altered slightly, said Sean Raymond, a postdoctoral researcher at the University of Colorado, who took part in the work while he was an astronomy doctoral student at the University of Washington.