Time evolution of the amplitude of the dominant spherical harmonics mode of the quantity A(t, r, θ) from Eq. (8). The second core radius is shown by the black line. The time t = 0 indicates the onset of the second core formation for the different collapse scenarios. Shown here is a small interval in time for the 1 M_⊙ (top left), 5 M_⊙ (top right), 10 M_⊙ (bottom left), and 20 M_⊙ (bottom right) cases.