Hydrodynamics of giant planet formation. I - Overviewing the kappa-mechanism
Abstract
The stability of layers in static, radiative gas spheres is analyzed. It is shown that stability depends only on the equations of state, the opacities, and the local thermodynamic state in the layer. Stability and instability can be expressed in the form of stability equations of state which are universal for a given composition. As an example, such equations are calculated for solar composition. Regions of instability are described and related to the underlying microphysical processes. Vibrational instability is found to be a common phenomenon at temperatures lower than the second He ionization zone. The kappa mechanism is widespread under cool conditions. The results are applied to a critical mass model of a protogiant planet in the nucleated instability hypothesis of giant planet formation and to protostellar cores. These objects are shown to be located in the dynamically large and vibrationally unstable regions associated with H2 dissociation and H ionization zones.
- Publication:
-
Astronomy and Astrophysics
- Pub Date:
- November 1990
- Bibcode:
- 1990A&A...238...83W
- Keywords:
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- Computational Astrophysics;
- Gas Giant Planets;
- Interstellar Gas;
- Planetary Evolution;
- Equations Of State;
- Hydrodynamics;
- Hydrogen;
- Protoplanets;
- Solar Physics;
- Stellar Composition;
- Astrophysics