Quick-n-dirty binary star simulation in AMUSE

From Micasim

Project	AMUSE
Project Lead	Simon Portegies Zwart
Project Homepage	AMUSE

In the top level directory (where amuse.sh lives), create a file binary.py with the following contents:

#!/usr/bin/python

import sys

from amuse.legacy.phiGRAPE.muse_dynamics_mpi import *

pg = PhiGRAPE()

pg.setup_module()
pg.add_particle(1, 1., 0.1, 1., 0., 0., 0, 0.5, 0.)
pg.add_particle(2, 1., 0.1, -1., 0., 0., 0., -0.5, 0.)
pg.initialize_particles(0.)

star1 = open("star1.dat", "w")
star2 = open("star2.dat", "w")

for i in range(100) :
    pg.evolve(0.1*i , 0)
    t = pg.get_time()
    star1data = pg.get_state(1)
    star2data = pg.get_state(2)

    star1.write("%.2f %.2f %.2f %.2f\n" %
                (t, star1data['x'], star1data['y'], star1data['z']) )
    star2.write("%.2f %.2f %.2f %.2f\n" %
                (t, star2data['x'], star2data['y'], star2data['z']) )

star1.close()
star2.close()

Then run:

./amuse.sh binary.py

When that finishes, you will have two files, "star1.dat" and "star2.dat", which are data files with 4 columns showing (t, x, y, z) for two orbiting stars in increments of 1 "time unit"... where the time unit is whatever make sense given the mass units and distance units and the assumption that G=1.

You can look at the jolly results with gnuplot, for example:

gnuplot> plot "star1.dat" using 1:2
gnuplot> set size ratio=1
gnuplot> plot "star1.dat" using 2:3