Can Giant Planets Form by Direct Gravitational Instability?

  title={Can Giant Planets Form by Direct Gravitational Instability?},
  author={Roman R. Rafikov},
  journal={The Astrophysical Journal Letters},
  pages={L69 - L72}
  • R. Rafikov
  • Published 22 June 2004
  • Physics, Geology
  • The Astrophysical Journal Letters
Gravitational instability has been invoked as a possible mechanism of the giant planet production in protoplanetary disks. Here we critically revise its viability by noting that to form planets directly, it is not enough for protoplanetary disks to be gravitationally unstable. They must also be able to cool efficiently (on a timescale comparable to the local disk orbital period) to allow the formation of the bound clumps by fragmentation. A combination of the dynamical and thermal constraints… 
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