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Homework Help: Astrophysics - Energy radiated from a star through contraction

  1. May 1, 2010 #1

    1. The problem statement, all variables and given/known data
    As the sun evolved to the main sequence it contracted under gravity and its internal temperature changed from 3E4 K to 6E6 K. Assuming the sun is fully ionised at these temperatures estimate the energy radiated during this phase, stating your assumptions.

    2. Relevant equations
    I think this involves using the equation for gravitational potential energy and possible the scaling relation; Temp proportional to Mass/Radius for stars.

    3. The attempt at a solution
    I am not sure how to attempt this, my thinking is the temperature increase corresponds to a pressure decrease over which the radius of the sun decreases, thus releasing gravitational potential energy. But how would i relate the temperature change to a radius change?

  2. jcsd
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