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Angular momentum loss by radiation gravitational

  1. Sep 12, 2013 #1
    Hi,

    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
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