Wednesday, February 10, 2010 - 3:15pm
Neal Turner (JPL):
"Where Planets Form: the Dead Zone in Protostellar Disks"
Abstract. The disks of gas and dust observed orbiting many young stars are surely the birthplaces of planets, and give dramatic confirmation of a picture of the origins of our solar system stretching back at least to Immanuel Kant. While the Hubble and Spitzer Space Telescopes and ground-based interferometers enable us to probe the disks' atmospheres and outer reaches, the growth of planets has not yet been directly observed, due to the great distances of even the nearest examples, and the fact that the dust obscures our view. These limitations mean that computer modeling is crucial for our understanding. I will show images from 3-D calculations of the internal flows driven by magnetic forces. Stellar X-rays absorbed in the disk atmosphere yield a magnetically-active turbulent layer overlying a poorly-conducting dead zone. Such a structure enables some dust to remain suspended in the atmosphere, as observed, while much of the solid material settles into the interior where it is assembled into planets.