I Help with the Virial Theorem please

AI Thread Summary
The discussion centers on calculating the kinetic energy of a star cluster composed of stars and gas, with specific masses and density distributions. The total mass of the gas is expressed as a fraction of the total mass of the stars. The relationship between kinetic energy (KE) and potential energy (PE) is established as 2KE + PE = 0, with formulas provided for both KE and PE. Participants emphasize the need for clearer mathematical notation to facilitate understanding of the equations involved. The conversation highlights the complexities of applying the virial theorem in astrophysical contexts.
Alfie114
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I have a question about the virial theorem as applied to a cluster of stars.
Anyone able to help if I provide you with more details?
 
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You might need to provide a bit more detail about your question.
 
OK we have a star cluster (the system) which is made up from stars (total mass M sub *) and gas (total mass M sub g). The stars and gas are all distributed as spheres of constant density and a finite radius r sub c.

The total mass of the stars and the gas is different but we can assume that M sub g = f*M sub *

If the system is unrotating and in equilibrium how do we calculate the kinetic energy in terms of r sub c, f and M sub *?

We can take 2KE + PE = 0 where KE = (-3/5) (GM^2/R) and PE = (3kT/2)*n where n is the total number of particles = (M/mu*m sub H) where mu=1 and m sub H is the mass of a hydrogen atom.
 
Alfie114 said:
OK we have a star cluster (the system) which is made up from stars (total mass M sub *) and gas (total mass M sub g). The stars and gas are all distributed as spheres of constant density and a finite radius r sub c.

The total mass of the stars and the gas is different but we can assume that M sub g = f*M sub *

If the system is unrotating and in equilibrium how do we calculate the kinetic energy in terms of r sub c, f and M sub *?

We can take 2KE + PE = 0 where KE = (-3/5) (GM^2/R) and PE = (3kT/2)*n where n is the total number of particles = (M/mu*m sub H) where mu=1 and m sub H is the mass of a hydrogen atom.
You need to use math latex notation. Its hard to understand your equations like this.
 
Ok I've got these where omega is the potential energy
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