Binary simulation

Our next intention is to consider the radiation effect of the AGB (primary) star in forming the fall back disk.

Roughly speaking, this will modify the hydrodynamical equations:

\[\frac{\partial \rho\mathbf{u}}{\partial t}+\nabla\cdot(\rho\mathbf{u}\mathbf{u})=-\nabla P-\nabla E-\nabla \Psi\]

Where stands for radiation energy density. Radiation driven wind is actually radiation-driven dusty wind. A portion of Radiation energy is transferred to dust's kinetic energy then transferred to gas kinetic or thermal energy. According to Poynting Flux theorem, we know that radiation energy density drop by . Neglect the inhomogeneity and non-linearity in energy transfer between radiation and dust, dust and wind, we can combine the radiation effect with gravity.

Assume the total radiation power of the AGB will fall in binary evolution. I use the following prescribed time dependent curve to illustrate this problem.

  1. Gravity Arctan(t)
  2. Wind speed, wind density or

The goal is to explore the parameters to get fall back phenomenon. Unfortunately, after two weeks of trial, the result is still not good.

Test A: gas is gravitationally bounded, no falling back process.

z0bounded.gif​

Test B: gas run away supersonically, no falling back.

The AGB seems to blow out all its envelop at some point, which looks as if I suddenly turned off the wind, but I did not.

z0escape.gif​

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