Tuesday, February 27, 2007
(Note: Special date, place, and time)
Planet Embryos in Vortex Wombs: The Origin of Planetary Systems
Joseph A. Barranco
Harvard-Smithsonian Center for Astrophysics
The past 15 years have witnessed the discovery of planets in the most unexpected of places: terrestrial-size planets around such "dead" stars as pulsars (Wolszczan 1991), gas giant planets that orbit their parent stars much closer than Mercury does our Sun (Mayor & Queloz 1995), and now even planets around "failed" stars known as brown dwarfs (Chauvin et al. 2005). Besides these unusual systems, astronomers have now discovered more than 200 planets around other Sun-like stars (Marcy et al. 2006, Fischer et al. 2006), and the search continues as we try to find a system that looks just like our own. Clearly, the mechanisms of planet formation are far more robust than we had first imagined. These new discoveries have sparked a Renaissance in planet formation theory, an understanding of which is inherently interdisciplinary, drawing on mechanics (both solid & fluid), thermodynamics, electromagnetism, astrophysics, and geophysics. I will present recent computational simulations of the settling of dust sub-layers in the protoplanetary disks of gas & dust out of which planets must form. Such dust sub-layers can be unstable to Kelvin-Helmholtz instabilities which can re-mix the gas and dust and prevent further settling, potentially inhibiting the formation of planetesimals, the first building blocks of planets. I will also describe alternative mechanisms to concentrate dust, including 3D vortices ("giant hurricanes") in protoplanetary disks, which trap dust grains in the "eyes" of such storms.
Refreshments at 11:00 AM. Seminar begins at 11:10 AM.
Building 4, Room 1-314
For further information, please call (909) 869-4014