Encyclopedia of Astrobiology

Living Edition
| Editors: Muriel Gargaud, William M. Irvine, Ricardo Amils, Henderson James Cleaves, Daniele Pinti, José Cernicharo Quintanilla, Michel Viso

Disk Instability, Model for Giant Planet Formation

  • Yann Alibert
  • Ravit Helled
Living reference work entry
DOI: https://doi.org/10.1007/978-3-642-27833-4_5109-1



The disk instability model suggests that gas giant planets form directly as a result of (local) gravitational instabilities in the protoplanetary disk. Numerical simulations have shown that clumps of about one to several Jupiter masses can form in sufficiently gravitationally unstable disks. Protoplanetary disks can become gravitationally unstable if they are sufficiently cool and/or massive. The condition for gravitational instability can be determined from the value of the Toomre parameter Q. Protoplanetary disks will be unstable for Q < ~1. Once a local instability occurs, a gravitationally bound sub-condensation region (clump) is created. If the cooling time in this region of the disk is shorter than (or comparable to) the dynamical time, the fragment contracts, and eventually evolves to become a giant planet.

See Also


Planet formation Protoplanetary disk Q (Toomre parameter) 

Copyright information

© Springer-Verlag Berlin Heidelberg 2014

Authors and Affiliations

  1. 1.Space Research and Planetary SciencesUniversity of Bern, Physics InstituteBernSwiss
  2. 2.Geophysical, Atmospheric and Planetary SciencesTel Aviv University, Raymond and Beverly Sackler Faculty of Exact ScienesTel AvivIsrael