December 9, 1999 CfA Colloquium


Title: Gas Giant Planet Formation: Core Accretion or Disk Instability?

Speaker: Alan Boss

Abstract: Suspected gas giant planets have been detected in orbit around nearly two dozen nearby stars, and a system of three objects has been found in orbit around Upsilon Andromedae. Two mechanisms have been suggested for forming gas giant planets, core accretion and disk instability. Core accretion, the generally accepted mechanism, requires several million years or more to form a gas giant planet in a protoplanetary disk like the solar nebula. Disk instability, on the other hand, can form a gas giant protoplanet in a few thousand years. However, disk instability has been thought to be possible only in relatively massive disks. New three dimensional hydrodynamics models suggest that a protoplanetary disk with a mass at the high end of the range considered likely for the solar nebula could form several giant gaseous protoplanets with orbits initially around 6 AU to 12 AU. Because this disk mass is similar to that apparently required for core accretion to succeed, disk instability may outrun the slower core accretion mechanism.

Student Lunch: TBA

Further Reading: 1997, Science, 276, 1836-1839