Simulating stellar winds in AMUSE
  We present stellar_wind.py, a module that provides multiple methods of
simulating stellar winds using smoothed particle hydrodynamics codes (SPH)
within the astrophysical multipurpose software environment (AMUSE) framework.
With the simple wind mode, we create SPH wind particles in a spherically
symmetric shell. We inject the wind particles with a velocity equal to their
terminal velocity. The accelerating wind mode is similar, but with this method
particles can be injected with a lower initial velocity than the terminal
velocity and they are accelerated away from the star according to an
acceleration function. With the heating wind mode, SPH particles are created
with zero initial velocity with respect to the star, but instead wind particles
are given an internal energy based on the integrated mechanical luminosity of
the star. This mode is designed to be used on longer timescales and larger
spatial scales compared to the other two modes and assumes that the star is
embedded in a gas cloud. For fast winds, we find that both the simple and
accelerating mode can reproduce the desired velocity, density and temperature
profiles. For slow winds, the simple wind mode is insufficient due to dominant
hydrodynamical effects that change the wind velocities. The accelerating mode,
with additional options to account for these hydrodynamical effects, can still
reproduce the desired wind profiles. We test the heating mode by simulating
both a normal wind and a supernova explosion of a single star in a uniform
density medium. The stellar wind simulation results matches the analytical
solution for an expanding wind bubble. The supernova simulation gives
qualitatively correct results, but the simulated bubble expands faster than the
analytical solution predicts. We conclude with an example of a triple star
system which includes the colliding winds of all three stars.
