Instabilities of Stellar Systems
Galaxies and star clusters can be unstable, if small perturbations in the gravitational potential cause changes in the density that reinforce the original perturbation. Such instabilities usually require that the motions of stars be highly correlated, so that the perturbation is not "smeared out" by random motions. After the instability has run its course, the system is typically "hotter" (the motions are more random) or rounder than before. Instabilities in stellar systems include:
- Bar instability of rapidly-rotating disks
- Jeans instability
- Firehose instability
- Gravothermal instability
- Radial-orbit instability
- Various instabilities in cold rotating disks
Read more about this topic: Instability
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