textbook example code: evolve_triple_with_wind.pyΒΆ

[source code]

"""
   N-body integration of N particles with a Salpeter initial mass
   function between Mmin and Mmax and with stellar evolution with
   metallicity z.
"""
import sys
import numpy
from optparse import OptionParser

from prepare_figure import single_frame
from distinct_colours import get_distinct

from amuse.units import units, constants, nbody_system
from amuse.units.quantities import zero
from amuse.datamodel import Particle, Particles
from amuse.support.console import set_printing_strategy
from amuse.io import store

from amuse.ext.orbital_elements import new_binary_from_orbital_elements
from amuse.ext.orbital_elements import orbital_elements_from_binary

from amuse.community.huayno.interface import Huayno
from amuse.community.smalln.interface import SmallN
from amuse.community.hermite0.interface import Hermite
from amuse.community.seba.interface import SeBa
from amuse.community.sse.interface import SSE

def orbital_period(a, Mtot):
    return 2*numpy.pi*(a**3/(constants.G*Mtot)).sqrt()

def semimajor_axis(P, Mtot):
    return (constants.G*Mtot*P**2/(4*numpy.pi**2))**(1./3)

def get_orbital_elements_of_triple(stars):
    inner_binary = stars[0]+stars[1]
    outer_binary = Particles(1)
    outer_binary[0].mass = inner_binary.mass.sum()
    outer_binary[0].position = inner_binary.center_of_mass()
    outer_binary[0].velocity = inner_binary.center_of_mass_velocity()
    outer_binary.add_particle(stars[2])
    M1, M2, ain, ein, ta_in, inc_in, lan_in, aop_in \
        = orbital_elements_from_binary(inner_binary, G=constants.G)
    M12, M3, aout, eout, ta_out, outc_out, lan_out, aop_out \
        = orbital_elements_from_binary(outer_binary, G=constants.G)
    return ain, ein, aout, eout

def evolve_triple_with_wind(M1, M2, M3, Pora, Pin_0, ain_0, aout_0,
                            ein_0, eout_0, t_end, nsteps, scheme, dtse_fac):

    import random
    from amuse.ext.solarsystem import get_position

    print "Initial masses:", M1, M2, M3
    t_stellar = 4.0|units.Myr
    triple = Particles(3)
    triple[0].mass = M1
    triple[1].mass = M2
    triple[2].mass = M3
    stellar = SeBa()
    stellar.particles.add_particles(triple)
    channel_from_stellar = stellar.particles.new_channel_to(triple)
    stellar.evolve_model(t_stellar)
    channel_from_stellar.copy_attributes(["mass"])
    M1 = triple[0].mass
    M2 = triple[1].mass
    M3 = triple[2].mass
    print "T=", stellar.model_time.in_(units.Myr)
    print "M=", stellar.particles.mass.in_(units.MSun)
    print "Masses at time T:", M1, M2, M3

    # Inner binary

    tmp_stars = Particles(2)
    tmp_stars[0].mass = M1
    tmp_stars[1].mass = M2

    if Pora == 1:
        ain_0 = semimajor_axis(Pin_0, M1+M2)
    else:
        Pin_0 = orbital_period(ain_0, M1+M2)

    print 'ain_0 =', ain_0
    print 'M1+M2 =', M1+M2
    print 'Pin_0 =', Pin_0.value_in(units.day), '[day]'
    #print 'semi:', semimajor_axis(Pin_0, M1+M2).value_in(units.AU), 'AU'
    #print 'period:', orbital_period(ain_0, M1+M2).value_in(units.day), '[day]'

    dt = 0.1*Pin_0
    ma = 180
    inc = 30
    aop = 180
    lon = 0
    r, v = get_position(M1, M2, ein_0, ain_0, ma, inc, aop, lon, dt)
    tmp_stars[1].position = r
    tmp_stars[1].velocity = v
    tmp_stars.move_to_center()

    # Outer binary

    r, v = get_position(M1+M2, M3, eout_0, aout_0, 0, 0, 0, 0, dt)
    tertiary = Particle()
    tertiary.mass = M3
    tertiary.position = r
    tertiary.velocity = v
    tmp_stars.add_particle(tertiary)
    tmp_stars.move_to_center()

    triple.position = tmp_stars.position
    triple.velocity = tmp_stars.velocity

    Mtriple = triple.mass.sum()
    Pout = orbital_period(aout_0, Mtriple)

    print "T=", stellar.model_time.in_(units.Myr)
    print "M=", stellar.particles.mass.in_(units.MSun)
    print "Pout=", Pout.in_(units.Myr)

    converter = nbody_system.nbody_to_si(triple.mass.sum(), aout_0)
    gravity = Hermite(converter)
    gravity.particles.add_particles(triple)

    channel_from_framework_to_gd = triple.new_channel_to(gravity.particles)
    channel_from_gd_to_framework = gravity.particles.new_channel_to(triple)

    Etot_init = gravity.kinetic_energy + gravity.potential_energy
    Etot_prev = Etot_init

    gravity.particles.move_to_center()

    time = 0.0 | t_end.unit
    ts = t_stellar + time

    ain, ein, aout, eout = get_orbital_elements_of_triple(triple)
    print "Triple elements t=",  time,  \
        "inner:", triple[0].mass, triple[1].mass, ain, ein, \
        "outer:", triple[2].mass, aout, eout

    dt_diag = t_end/float(nsteps)
    t_diag = dt_diag

    t = [time.value_in(units.Myr)]
    smai = [ain/ain_0]
    ecci = [ein/ein_0]
    smao = [aout/aout_0]
    ecco = [eout/eout_0]
    ain = ain_0

    def advance_stellar(ts, dt):
        E0 = gravity.kinetic_energy + gravity.potential_energy
        ts += dt
        stellar.evolve_model(ts)
        channel_from_stellar.copy_attributes(["mass"])
        channel_from_framework_to_gd.copy_attributes(["mass"])
        return ts, gravity.kinetic_energy + gravity.potential_energy - E0

    def advance_gravity(tg, dt):
        tg += dt
        gravity.evolve_model(tg)
        channel_from_gd_to_framework.copy()
        return tg

    while time < t_end:

        Pin = orbital_period(ain, triple[0].mass+triple[1].mass)
        dt = dtse_fac*Pin
        dt *= random.random()

        if scheme == 1:

            ts, dE_se = advance_stellar(ts, dt)
            time = advance_gravity(time, dt)

        elif scheme == 2:

            time = advance_gravity(time, dt)
            ts, dE_se = advance_stellar(ts, dt)

        else:

            dE_se = zero
            #ts, dE_se = advance_stellar(ts, dt/2)
            time = advance_gravity(time, dt)
            #ts, dE = advance_stellar(ts, dt/2)
            #dE_se += dE

        if time >= t_diag:

            t_diag = time + dt_diag

            Ekin = gravity.kinetic_energy
            Epot = gravity.potential_energy
            Etot = Ekin + Epot
            dE = Etot_prev - Etot
            Mtot = triple.mass.sum()
            print "T=", time,
            print "M=", Mtot, "(dM[SE]=", Mtot/Mtriple, ")",
            print "E= ", Etot, "Q= ", Ekin/Epot,
            print "dE=", (Etot_init-Etot)/Etot, "ddE=", (Etot_prev-Etot)/Etot,
            print "(dE[SE]=", dE_se/Etot, ")"
            Etot_init -= dE
            Etot_prev = Etot
            ain, ein, aout, eout = get_orbital_elements_of_triple(triple)
            print "Triple elements t=",  (4|units.Myr) + time,  \
                "inner:", triple[0].mass, triple[1].mass, ain, ein, \
                "outer:", triple[2].mass, aout, eout

            t.append(time.value_in(units.Myr))
            smai.append(ain/ain_0)
            ecci.append(ein/ein_0)
            smao.append(aout/aout_0)
            ecco.append(eout/eout_0)

            if eout > 1.0 or aout <= zero:
                print "Binary ionized or merged"
                break

    gravity.stop()
    stellar.stop()

    return t, smai, ecci, smao, ecco

def main(M1, M2, M3, Pora, Pin, ain, aout, ein, eout,
         t_end, nsteps, scheme, dtse_fac):

    from matplotlib import pyplot

    x_label = "$a/a_{0}$"
    y_label = "$e/e_{0}$"
    fig = single_frame(x_label, y_label, logx=False, logy=False,
                       xsize=10, ysize=8)
    color = get_distinct(4)

    if scheme == 0:
        srange = [1,2,3]
    else:
        srange = [scheme]

    i = 0
    for s in srange:
        time, ai, ei, ao, eo = evolve_triple_with_wind(M1, M2, M3,
                                                       Pora, Pin,
                                                       ain, aout,
                                                       ein, eout,
                                                       t_end, nsteps,
                                                       s, dtse_fac)
        if i == 0:
            pyplot.plot(ai, ei, c=color[0], label='inner')
            pyplot.plot(ao, eo, c=color[1], label='outer')
            i = 1
        else:
            pyplot.plot(ai, ei, c=color[0])
            pyplot.plot(ao, eo, c=color[1])

    pyplot.legend(loc='best', ncol=1, shadow=False, fontsize=20)

    #save_file = 'evolve_triple_with_wind.png'
    save_file = 'evolve_triple_with_wind' \
                    +'_s={:d}_dtse={:.3f}'.format(scheme, dtse_fac) \
                    +'.png'
    pyplot.savefig(save_file)
    print '\nSaved figure in file', save_file,'\n'
    pyplot.show()

def new_option_parser():

    from amuse.units.optparse import OptionParser
    result = OptionParser()
    result.add_option("-n",
                      dest="nsteps", type="int", default = 10000,
                      help="diagnostic time steps [%default]")
    result.add_option("--M1", unit=units.MSun,
                      dest="M1", type="float", default = 60 | units.MSun,
                      help="Primary mass [%default]")
    result.add_option("--M2", unit=units.MSun,
                      dest="M2", type="float", default = 30 | units.MSun,
                      help="secondary mass [%default]")
    result.add_option("--M3", unit=units.MSun,
                      dest="M3", type="float", default = 20 | units.MSun,
                      help="secondary mass [%default]")
    result.add_option("--Pora",
                      dest="Pora", type="int", default = 1,
                      help="period (1) or semimajor axis (2) [%default]")
    result.add_option("--Pin", unit=units.day,
                      dest="Pin", type="float", default = 19|units.day,
                      help="orbital period [%default]")
    result.add_option("--ain", unit=units.AU,
                      dest="ain", type="float", default = 0.63|units.AU,
                      help="orbital separation [%default]")
    result.add_option("--aout", unit=units.AU,
                      dest="aout", type="float", default = 100|units.AU,
                      help="orbital separation [%default]")
    result.add_option("--ein",
                      dest="ein", type="float", default = 0.2,
                      help="orbital eccentricity [%default]")
    result.add_option("--eout",
                      dest="eout", type="float", default = 0.6,
                      help="orbital eccentricity [%default]")
    result.add_option("-t", unit=units.Myr,
                      dest="t_end", type="float", default = 0.55 | units.Myr,
                      help="end time of the simulation [%default]")
    result.add_option("-s",
                      dest="scheme", type="int", default = 3,
                      help="integration scheme [%default]")
    result.add_option("--dtse",
                      dest="dtse_fac", type="float", default = 0.1,
                      help="stellar mass-loss time step fraction [%default]")
    return result

if __name__ in ('__main__', '__plot__'):

    set_printing_strategy("custom",
                          preferred_units = [units.MSun, units.AU, units.Myr],
                          precision = 12, prefix = "",
                          separator = " [", suffix = "]")

    o, arguments  = new_option_parser().parse_args()
    main(**o.__dict__)

Keywords: python, amuse, astrophysics, matplotlib, pylab, example, codex (see how-to-search-examples)