How Do You Calculate the Mass of a Star in Orbit?

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SUMMARY

The discussion focuses on calculating the mass of a star in orbit, specifically Star A, which orbits a point P with a radius R and period T. The key equation derived is GM = 4π²R³/T², which calculates the mass of the central body being orbited, assuming it is significantly more massive than the star. If the central body is less massive, the calculated mass will approximate the mass of the star itself. The ambiguity in the problem regarding the mass of the orbiting body is acknowledged, emphasizing the need for clarity in such calculations.

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  • Understanding of Newton's Law of Universal Gravitation
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Homework Statement



Star A is in a circular orbit of radius R around point P. The period of the star is T. Determine the mass of the Star


Homework Equations


I do not know how to find the mass of the orbiting body. I found the centripetal acceleration which equaled GM/R^2. I could find the mass of P, but not the orbiting body


The Attempt at a Solution

I said that V=2piR/T. then that GM=4pi^2R^3/T^2. But that only gives me the mass of the body the star is orbiting around... Right?
 
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I think you're right, at least if you assume that the other body is much more massive than the star itself. Then again, if the other body is much lighter than the star, the mass you find is pretty close to the mass of the star. But the problem doesn't say anything about the other body, so I'm not sure what the intent is.

I'll bring this to the attention of other homework helpers and perhaps one of them will have some insight.
 

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