Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Angular momentum loss by radiation gravitational

  1. Sep 12, 2013 #1

    The evolution of a close binary is driven by angular momentum loss to gravitational
    radiation, so that

    (dJ/dt)/J = -(32G^3 M1*M2*(M1 + M2))/5*(c^5)* a^4

    From relations mass-radius, (-dM2/dt)/M2 = -(dJ/dt)/J / (4/3 - q) and

    R2/a = ((M2)/(M1 + M2))^(1/3)* (0.462)

    M2 = m2*Mo, M1 = m1*Mo m2~R2/Ro

    I calculated dM/dt ~ 10^-10*(P/2(h))^(-2/3)*Mo/yr for for main-sequence...

    But when the secondary becomes degenerate the relations change.

    A degenerate star has a mass–radius relation of the form: R2 = Km2^(-1/3) and

    P ∝ M2 ^-1, K = 2x10^9cm and (-dM2/dt)/M2 = -(dJ/dt)/J / (2/3 - q) .

    I need show that dM/dt ~ 10^-12*(P/2(h))^(-14/3)*Mo/yr. But ,already tried very unsuccessfully.

    THis is a question of book : accretion power in astrophisics (JUAN FRANK) cap 4 ,ex 3

    thank you very much.
    Last edited: Sep 12, 2013
  2. jcsd
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook

Can you offer guidance or do you also need help?
Draft saved Draft deleted