spacetoday.net: Study shows gas giants form rapidly

Posted: Mon, Dec 2, 2002, 8:38 AM ET (1338 GMT)
Protoplanetary disk computer model image (U. Wash.)

Gas giant planets like Jupiter may form in just hundreds of years, not the millions of years previously thought, scientists reported last week. In a paper published in Friday's issue of the journal Science, scientists from the US, Canada, and Switzerland used new computer models to show that protoplanetary disks around young stars break up after just a few orbits. Since gas giants require a large amount of material from the disk, the planets must form quickly — within a few hundred years — or else the disk will break up too much to allow the planets to form at all. The model also explains why Uranus and Neptune are smaller than Jupiter and Saturn: the more distant, smaller planets most likely lost gas from a passing nearby star. This work builds on research by other scientists, including Alan Boss of the Carnegie Institution of Washington, who previously estimated that a Jupiter-sized planet could form in about 1,000 years.