1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Density at the centre of the sun

  1. Oct 15, 2014 #1
    Hello, here is the question I have to answer;

    I am aware that the gravitational energy of one layer of thickness dr is
    [itex]dU=-\frac{GM(r)dm}{r}[/itex]​
    and that ultimately I will have to integrate this over all radii but I am unclear about the expression for [itex]\rho_{center}[/itex]. The only thing that springs to mind is
    [itex]\rho=\frac{M}{\frac{4}{3}\pi R^3}[/itex]​
    but this must be for an average density over the whole star. Can anyone point me in the direction of how to establish an expression for [itex]\rho_{center}[/itex]?

    Thanks a lot
     
  2. jcsd
  3. Oct 15, 2014 #2

    jedishrfu

    Staff: Mentor

    It says in the problem that it is the density at the center ie r=0 its just a constant scalar.

    so you must construct a function M(r) using p(r) for the shell.
     
  4. Oct 15, 2014 #3
    However the question says "give an expression for [itex]\rho_{center}[/itex], so presumably I have to calculate the value of [itex]\rho_{center}[/itex] from scratch rather than looking it up. For example I know that the value for the center density quoted from many sources is [itex]1.622\times10^5\textrm{ kg m}^{-3}[/itex] however it is clear from the question I cannot simply use this value but I need to form an expression and then set r=0, but anything I try always ends up with r in the denominator thus resulting in infinity.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted



Similar Discussions: Density at the centre of the sun
  1. Centre of Mass (Replies: 1)

  2. Centre of charge ? (Replies: 2)

  3. Centre of mass (Replies: 2)

  4. Sun Help (Replies: 1)

  5. Centre of mass (Replies: 3)

Loading...