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New clues about the birth of planets

January 16, 2009 -- Scientists know that planets are born out of the dust and gas that orbits young stars, but how tiny grains of dust collide to form the building blocks of planets remains a mystery. New research by Assistant Professor of Astronomy Joseph Barranco shows that turbulence could create conditions ripe for the birth of new planets.

A sequence of five images showing how turbulent forces mix up the layers of dust and gas orbiting young stars. The images show the transition from a layer of dust flanked by two layers of gas to scenario where the dust and gas are mixed.

Barranco uses three-dimensional simulations to demonstrate how turbulence causes the dust and gas surrounding young stars to swirl and mix in a similar way to ocean waves or hurricanes. His study suggests turbulence is an obstacle to gravitational instability -- the prevailing planet formation theory since the 1970s. According to gravitational instability theory, dust and gas will settle into a very dense, thin layer until it reaches a critical point and crumbles into kilometer-sized clumps. But Barranco's study proposes that turbulence prevents the dust and gas from reaching this critical point.

"These results defy the proposed solution of how planets are formed," said Barranco, whose models help explain processes that telescopes are not yet powerful enough to observe. "These new simulations open new avenues of investigation. It could be that in the quiet center of a hurricane-like storm, dust can collect and get trapped, seeding the beginnings of planet formation."

Barranco's new research will be published in the Jan. 20 issue of The Astrophysical Journal. A short animation from Barranco's research can be viewed at the following web site:








Left: A series of images showing how turbulent forces mix up the layers of dust and gas orbiting young stars. Images depict a 2-D slice through Barranco's 3-D simulations. Deep red indicates dust-rich gas. Deep blue indicates pure gas. Credit: Joseph Barranco

-- Elaine Bible


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