Posted on Nov. 28: Scientists show planets created in hundreds, not millions, of years

By Shelly Easton, November 28, 2002

McMaster researcher James Wadsley has helped demonstrate that large gaseous planets like Jupiter could be created in hundreds, not millions of years, as previously believed.

The research associate with SHARCNET (Shared Hierarchical Academic
Research Computing Network) is part of a team of international astrophysicists from the U.S. and Switzerland, who have successfully
created the first computer simulation that shows giant gaseous planets can be formed quickly.

Their research is published in today's edition of Science.

Wadsley became involved when he developed the gas computer code used for the research as a post-doctoral fellow while at the University of Washington in Seattle. Lucio Mayer, of the University of Zurich, is the lead author. The co-authors are University of Washington astrophysicist Thomas Quinn and Joachim Stadel, formerly of the University of Victoria in British Columbia and now at the University of Zurich.

The popular theory holds that rocky planets like Earth were created as rocks orbiting in a disk around the young sun continuously collided, sticking to form larger and larger objects. Further
from the sun, the collision process is thought to take millions of years. This theory is more difficult to accept for giant gaseous planets like Jupiter and Saturn because the planets have to form before nearby bright stars can disperse the gases that must be added to the theoretical rocky core. The new approach assumes that the disk is heavy with gas that can fragment under its own gravity to
form gas giant planets in just a few hundred years without a preceding rocky stage.

Now with tools like the Hubble Space Telescope, astronomers can see "proto-stars" forming with disks around them.

"Observationally it appears that these disks are destroyed relatively quickly. Ours is the first simulation that actually forms Jupiter-like objects fast enough," said Wadsley. "Others have argued
that this should work, but this is the first time it's been conclusively demonstrated. If you can make them very quickly then it is reasonable to expect gas giants to be fairly common around other
stars."

Since the mid-1990s, scientists have discovered more than 100 planets - ranging from the mass of Jupiter to 10 times its size - orbiting stars outside our solar system.

Photo caption: "Forming Giant Planets via Fragmentation of Protoplanetary Disks"