[Baps] Goldreich talk, March 10, 4pm, MIT

[Sarah T. Stewart-Mukhopadhyay]

Thursday, March 10, 2005

HARRIS LECTURE

PETER GOLDREICH
  The Institute of Advanced Study

"Progress and Problems in Understanding Planet Formation"

I shall briefly review modern scenarios for planet formation. The growth of
the smallest gravitationally active bodies, planetesimals, is mired in
controversy. Orderly growth by the merging of planetesimals is followed by
runaway accretion in which a small fraction of the bodies grow much larger
than all the others. When these big bodies are sparse enough, runaway growth
gives way to oligarchic growth during which the big bodies grow in lockstep,
maintaining similar masses and uniformly spaced orbits. As oligarchs grow,
their orbital spacing increases and their number decreases.

My focus will be on how oligarchy ends and what happens after it does. I
will address three major questions regarding solar system planets:

  1. What determined their number?
  2. Why are their orbits nearly circular and coplanar?
  3. How long did they take to form?

Answers to these questions will be given in terms of stability against large
scale chaos; dynamical friction by small bodies; the accretion rate at the
geometrical cross section in the inner planet region, and the ejection rate
at the gravitationally enhanced cross section in the outer planet region.

Time: 4:15 pm
  Place: Room 10-250 / MIT

  Refreshments @ 3:45 pm in 4-339 (Physics Common Room).


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