Schedule Mar 18, 2004
Re'em Sari (CALTECH)

Clean up of small bodies which were not accreted onto protoplanets was the last and longest stage in planet formation. After oligarchy, protoplanets cleared wide gaps around their orbits which shut off the accretion of small bodies from just outside their Hill radii. Gravitational instability in the disk of small bodies produced larger ones whose random velocities were excited until their orbits crossed those of neighboring protoplanets. In the inner planet system, these bodies were ultimately incorporated into planets that continued to grow. In the the outer planet system these bodies were ejected and either took up residence in the Oort cloud or escaped from the sun. An important distinction between the formation of inner and outer planets is that growth of the former continued through clean up, whereas formation of the latter was essential complete by the end of oligarchy. This implies that the surface density of the proptoplanetary disk was that of the minimum solar mass nebula in the inner planet region but about six times larger in the outer planet region. The timescale through clean up was set by the accretion rate at the geometrical cross section in the inner planet region, and by the ejection rate at the gravitationally enhanced cross section in the outer planet region. It was a few hundred million years in the former and a few billion years in the latter. The Oort cloud, should therefore contain as much mass in larger than earth objects as in kilometer size bodies. Both originate in the outer planetary region.

Begin WebCam and audio for the whole talk: high bandwidth or medium bandwidth.
Or, begin audio only for the whole talk: high bandwidth or low bandwidth. (Or, right-click to download the whole audio file.)

Begin QuickTime of the whole talk (high bandwidth).

To begin viewing slides, click on the first slide below. (Or, view as pdf.)

[01] [02] [03] [04] [05] [06] [07] [08] [09] [10] [11] [12] [13] [14] [15] [16] [17] [18] [19] [20] [21] [22]

Author entry (protected)