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Jeans Length/Cloud Collapse

  1. Feb 25, 2013 #1

    As I understand, the following formula describes the Jeans length.

    [itex] \lambda_j = \sqrt\frac{15k_BT}{4\pi G \mu P} [/itex]

    Where [itex] \mu [/itex] is the mass per particle.

    Forgive me if this question may come across as relatively stupid, I imagine that each of the particles within the cloud should have different masses. Is [itex] \mu [/itex] an average of the masses?
  2. jcsd
  3. Feb 26, 2013 #2
    Yeah it is, but since most gas is generally ~75% H and ~25% He or something close to that, it's easy to figure out the average mass per particle.
  4. Feb 26, 2013 #3


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    It's one of those n-body things where you must approximate to get a numerical solution.
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