Equation for Solid Planet Structure

AI Thread Summary
The discussion focuses on finding a radial equation to determine the pressure or density of a moon or rocky planet, with references to Young's modulus and Poisson's ratio. Participants suggest starting with the equation of hydrostatic equilibrium, which is applicable to both fluid and elastic medium models. There is a mention of resources, including books on Newtonian models of stellar structure and geophysics, to aid in understanding. One user expresses difficulty in comprehending advanced materials, specifically regarding composite polytropes from Chandrasekhar's work. The conversation emphasizes the need for a solid planet equation similar to Emden's equation for further exploration.
Helios
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I'm looking for an radial equation to find the pressure or density of the interior of a moon or rock planet. It would involve Young's modulus or Poisson's ratio or something like. Any help?
 
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Well, you should probably start with something more basic: the equation of hydrostatic equilibrium. This is relevant to models in which you model a planet or star as a ball of fluid, but also to models in which you model it as an (isotropic, inhomogeneous) elastic medium. I take it you are looking for a Newtonian model? There are many books on Newtonian models of stellar structure, also many books on geophysics.
 
There are books on geophysics? Really? Your reply is kind of a downer. I've solved hydrostatic eq'ns for spheres and I'm looking for a next thing to do.
 
Hi Helios!

Maybe this one is what you are looking for: http://articles.adsabs.harvard.edu/cgi-bin/nph-iarticle_query?1980LPSC...11.1999A&data_type=PDF_HIGH&type=PRINTER&filetype=.pdf
I'm not so good at math and physics, so I don't really understand everything in the text. If you can use the formulas in the text to find density (and temperature), please tell me how!
 
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The next thing after fluid balls in hydrostatic equilibrium?

Hi, Helios,

Helios said:
There are books on geophysics? Really? Your reply is kind of a downer. I've solved hydrostatic eq'ns for spheres and I'm looking for a next thing to do.

Sorry if I underestimated your previous experience. Should I infer from your handle that you are particularly interested in stellar interiors? Would adding rotation whet your appetite? If so, if you know about McLaurin spheroids, I suppose the obvious next question is: have you studied Chandrasekhar, Selected Papers, esp. Vols 1, 4? That should keep you happy for a while!
 
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Hi Chris. I have Chandra's book "Stellar Interiors" and that's it. Out of it I'm trying to understand his explanation of composite polytropes. I don't get it and there are no examples.
Anyway I'm looking for a solid planet equation that might resemble Emden's eq'n.
 

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