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Homework Help: Mass of star problem

  1. Mar 2, 2014 #1
    hi, this is my first post here as i have driven insane by a math problem for my final year astronomy class, ive been at it for 3 hours and i can't make sense of it

    is the question even correct as i have made the assumption that the volume of a sphere times the density would give me 4 were there is a 2 and the density p instead of the density constant pc?
  2. jcsd
  3. Mar 2, 2014 #2


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    The density of the star is not constant throughout its volume. The expression for the density in section (1a) should be written

    ρ(r) = ρ[itex]_{c}[/itex](1 - (r/R)[itex]^{3}[/itex])

    for clarity. In order to derive M(r) and the total mass, you must do some integrations.
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