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Gravitationally bound, ionized cloud of hydrogen

  1. Apr 5, 2008 #1
    An isolated, spherical cloud of ionized hydrogen at temperature T initially nears gravitational-electromagnetic equilibrium. How will the cloud's structure evolve?
  2. jcsd
  3. Apr 5, 2008 #2


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    Is there a more specific question buried here, about protostars, or nebulae, or HII regions, or is this purely theoretical?
  4. Apr 6, 2008 #3
    I would like to know what eventually manifests from the given theoretical state: whether the cloud remains spherically symmetric; whether the situation is stable; what known bodies (like the ones you mention) might coalesce from such an idealization; and the relation between temperature and size (analogous to the Jeans radius) of this significantly charged cloud.
  5. Apr 25, 2008 #4
    everytime I think of this I get a different answer, makes my head spin....

    first I thought you meant a cloud of COMPLETELY ionized hydrogen. but if you consider two ionized H atoms (i.e. protons), the repulsive eletrostatic force will overpower the attractive garvitational force by a factor of 10^36, so they will just fly apart. there cannot be any equilibrium position because both forces go down with 1/r^2.

    so I guess you meant PARTIALLY ionized. consider two clouds, each containing 10^36 neutral H atoms and one ionized H+ atom. when one cloud looks at the other it will neither be repulsed nor attracted, there is gravitational-electrostatic equilibrium. so you might as well unite both clouds, or an arbitrary number of them, you just have to maintain the relation of 1 / 1^36 from charged to noncharged atoms.

    but as both forces are in equilibrium, the escape-velocity of the system is 0 (for a charged H+ atom). since you have a temperature T, and an assoicated velocitey distribution, the fastest H+ atoms will leave the cloud very quickly. until for the remaining H+ atoms the gravitational force will dominate, so there is a non-zero escape velocity and only a few (the fastest H+ atoms in the velocity distribution) can escape.
  6. Apr 26, 2008 #5


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    Gravitationally bound, ionized cloud of hydrogen
    Your question can only be answered by looking at your assumptions. How did the hydrogen became a “cloud”?

    The Phase Diagram of Strongly-Interacting Matter
    Authors: P. Braun-Munzinger, J. Wambach
    (Submitted on 28 Jan 2008)
    Phase transition from hadronic matter to quark matter
    Authors: P. Wang, A. W. Thomas, A. G. Williams
    last revised 3 Apr 2007
    The phase transition from nuclear matter to quark matter is always first order, whereas the transition between color superconducting quark matter and normal quark matter is second order. The phase transition between hadronic matter and quark matter can only occur at high density or temperature.
    I have more links in this blog entry
    https://www.physicsforums.com/blogs/jal-58039/warm-dense-matter-wdm-solid-hydrogen-1291/ [Broken]
    Last edited by a moderator: May 3, 2017
  7. Apr 26, 2008 #6

    At first glance, I do not understand the application of the articles you cite to a problem of electrodynamics. Perhaps you would condense your ideas into a paragraph or two.

    The hydrogen in my question would have become a cloud much like any nebula originally evolved from a collection of gas. A certain percentage of the cloud is assumed ionized as the whole reaches a quasi-gravitational equilibrium. What are the relatively stable states of this gas, like nebulae and protostars, and more importantly, what might cause electromagnetic disequilibrium there?
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