def displace_galaxy(galaxy, rotation_mat, translation_vector, radial_velocity,
transverse_velocity):
widgets = [
'Adjusting relative velocities and orientations: ',
pbwg.AnimatedMarker(),
pbwg.EndMsg()
]
with pbar.ProgressBar(widgets=widgets, fd=sys.stdout) as progress:
displaced_galaxy = Particles(len(galaxy))
displaced_galaxy.mass = galaxy.mass
displaced_galaxy.position = galaxy.position
displaced_galaxy.velocity = galaxy.velocity
for body in displaced_galaxy:
body.position = ([
body.x.value_in(units.kpc),
body.y.value_in(units.kpc),
body.z.value_in(units.kpc)
] @ rotation_mat) | units.kpc
body.velocity = ([
body.vx.value_in(units.kms),
body.vy.value_in(units.kms),
body.vz.value_in(units.kms)
] @ rotation_mat) | units.kms
displaced_galaxy.position += translation_vector
displaced_galaxy.velocity += radial_velocity
displaced_galaxy.velocity += transverse_velocity
return displaced_galaxy
def test_particles(galaxy, n_halo, n_bulge, n_disk):
_dsk = Particles(len(galaxy))
_dsk.mass = galaxy.mass
_dsk.position = galaxy.position
_dsk.velocity = galaxy.velocity
disk = _dsk[n_bulge:n_halo]
return disk
def new_system():
'''
Define the bodies here:
'''
particles = Particles(3)
planet_1 = particles[0]
planet_1.mass = 1.0 | units.MSun
planet_1.radius = 1.0 | units.RSun
planet_1.position = (855251, -804836, -3186) | units.km
planet_1.velocity = (7.893, 11.894, 0.20642) | (units.m / units.s)
planet_2 = particles[1]
planet_2.mass = 0.0025642 | units.MJupiter
planet_2.radius = 3026.0 | units.km
planet_2.position = (-0.3767, 0.60159, 0.03930) | units.AU
planet_2.velocity = (-29.7725, -18.849, 0.795) | units.kms
planet_3 = particles[2]
planet_3.mass = 1.0 | units.MEarth
planet_3.radius = 1.0 | units.REarth
planet_3.position = (-0.98561, 0.0762, -7.847e-5) | units.AU
planet_3.velocity = (-2.927, -29.803, -0.0005327) | units.kms
particles.move_to_center()
return particles
def bbh_hvgc(bbh_mass, mass_ratio, bbh_separation, bbh_phase, gc_closest,
gc_vinf):
"""Creates particle list, defines circular-planar BBH orbit, places GC. """
bh1_mass = bbh_mass / (1 + mass_ratio)
bh2_mass = mass_ratio * bh1_mass
r1, r2, v1, v2 = bbh_orbit(bbh_mass, mass_ratio, bbh_separation)
particles = Particles(3)
bh1 = particles[0]
bh1.mass = bh1_mass
bh1.position = (r1 * math.cos(bbh_phase), r1 * math.sin(bbh_phase),
0 | units.km)
bh1.velocity = (-v1 * math.sin(bbh_phase), v1 * math.cos(bbh_phase),
0 | units.kms)
#bh1.position = (0,r1,0)
#bh1.velocity = (-v1,0,0)
bh2 = particles[1]
bh2.mass = bh2_mass
bh2.position = (-r2 * math.cos(bbh_phase), -r2 * math.sin(bbh_phase),
0 | units.km)
bh2.velocity = (v2 * math.sin(bbh_phase), -v2 * math.cos(bbh_phase),
0 | units.kms)
# bh2.position = (0,-r2,0)
# bh2.velocity = (v1,0,0)
b = impact_parameter(bbh_mass, gc_closest, gc_vinf)
hvgc = particles[2]
hvgc.mass = 1.0e7 | units.MSun
hvgc.position = (b, -100, 0) | units.parsec
hvgc.velocity = (0 | units.kms, gc_vinf, 0 | units.kms)
particles.move_to_center()
return particles
def resolve_collision(collision_detection, gravity, bodies):
if collision_detection.is_set():
for ci in range(len(collision_detection.particles(0))):
encountering_particles = Particles(particles=[collision_detection.particles(0)[ci],
collision_detection.particles(1)[ci]])
colliding_particles = encountering_particles.get_intersecting_subset_in(bodies)
merge_two_particles(bodies, colliding_particles)
bodies.synchronize_to(gravity.particles)
def resolve_collision(collision_detection, gravity_code, bodies, time):
print("Well, we have an actual collision between two or more objects.")
print("This happened at time=", time.in_(units.yr))
for ci in range(len(collision_detection.particles(0))): # Multiple pairs of collisions could take place in one timestep
encountering_particles = Particles(particles=[collision_detection.particles(0)[ci],
collision_detection.particles(1)[ci]])
colliding_objects = encountering_particles.get_intersecting_subset_in(bodies)
merge_two_bodies(bodies, colliding_objects)
bodies.synchronize_to(gravity_code.particles) # Update bodies to contain 1 particle instead of 2
def add_comet_objects(pre_tack_giants_system, N_objects, comet_positions,
comet_velocities):
for i in tqdm(range(N_objects)):
comet = Particles(1)
comet.name = "OORT_" + str(i)
comet.mass = 0.0 | units.MSun #Take massless test particles
comet.radius = 0.0 | units.RSun
comet.position = (comet_positions[i, 0], comet_positions[i, 1],
comet_positions[i, 2])
comet.velocity = (comet_velocities[i, 0], comet_velocities[i, 1],
comet_velocities[i, 2])
comet.density = 0.0 | (units.MSun / (units.RSun**3))
pre_tack_giants_system.add_particle(comet)
z_comp = np.arctan(
100 / 8500.
) #Determining the z-component of the sun's trajectory around the galactic center
for i in range(len(pre_tack_giants_system)
): #adding the sun's trajectory around the galactic center
pre_tack_giants_system[i].position += (1, 0, 0) * (8.5 | units.kpc)
pre_tack_giants_system[i].velocity += (0, np.sqrt(1 - z_comp**2),
z_comp) * (220 | units.kms)
return pre_tack_giants_system
def Nstars():
particles = Particles(Ntracker)
i = 0
while i < Ntracker:
#here we generate our N bodies, we can change code in here to reflect different things
#We can distribut them randomly, have them near eachother, all at the same radius etc.
#All particles are in the x-y plane, this should still be adjusted accordingly to give some z randomization
#For now I will keep the mass the same and distribute uniformly over a circle
smallangle = random.random(
) * 2 * math.pi #smallangle is angle around solarpos, angle is angle around Sag A
radius = neighbourradius * math.sqrt(
random.random()) #sqrt so it's uniform and not clumped at r=0
particles[i].mass = 5 | units.MSun
particles[i].radius = 1.5 | units.RSun
#I have no z displacement, I can still add this though
particles[i].position = (radius * math.cos(smallangle) +
Solarposition[0],
radius * math.sin(smallangle) +
Solarposition[1], Solarposition[2])
#arctan only -pi/2 to pi/2, this codes gives us from -pi/2 to 3pi/2, we need global angle to fix vel vector
if particles[i].x < 0 | units.kpc:
angle = math.atan(particles[i].y / particles[i].x) + math.pi
else:
angle = math.atan(particles[i].y / particles[i].x)
#print(360*angle/(2*math.pi)) you can check that the angles are correct this way
particles[i].velocity = [
math.sin(angle) * vel + VelocityMilky[0],
-math.cos(angle) * vel + VelocityMilky[1], VelocityMilky[2]
]
i += 1
return particles
def MW_and_M31():
MW_M31 = Particles(2 + 2 * N)
MW = MW_M31[0]
MW.mass = 1 * 10**11 | units.MSun
MW.position = (0, 0, 0) | units.kpc
MW.velocity = (10, 10, 0) | units.kms
#MW.u = 0.5*(math.sqrt(2)*10)**2*1000*1000 | units.m**2 * units.s**-2
for i in range(N):
MW_M31[1 + i].mass = 10 | units.MSun
angle = random.random() * 2 * math.pi
MW_M31[1 + i].position = (r * math.cos(angle), r * math.sin(angle),
0) | units.kpc
MW_M31[1 + i].velocity = (10 + v * math.sin(angle),
10 - math.cos(angle) * v, 0) | units.kms
#Tried to add energy thing since Fi wanted it but didn't work
#MW_M31[1+i].u = 0.5*(math.sqrt((10 + v*math.sin(angle))**2+10 - math.cos(angle)*v))**2*1000*1000 | units.m**2 * units.s**-2
M31 = MW_M31[N + 1]
M31.mass = 1.6 * 10**11 | units.MSun
M31.position = (780, 0, 0) | units.kpc
M31.velocity = (0, 0, 0) | units.kms
for i in range(N):
MW_M31[N + 2 + i].mass = 10 | units.MSun
angle = random.random() * 2 * math.pi
MW_M31[N + 2 + i].position = (780 + r * math.cos(angle),
r * math.sin(angle), 0) | units.kpc
MW_M31[N + 2 + i].velocity = (v * math.sin(angle),
-math.cos(angle) * v, 0) | units.kms
#MW_M31[N+2+i].u = 0.5*230**2*1000*1000 | units.m**2 * units.s**-2
return MW_M31
def body_init_sun_jupiter():
particles = Particles(2)
sun = particles[0]
sun.mass = 1.0 | units.MSun
sun.radius = 1.0 | units.RSun
sun.position = (855251, -804836, -3186) | units.km
sun.velocity = (7.893, 11.894, 0.20642) | (units.m / units.s)
jupiter = particles[1]
jupiter.mass = 1.0 | units.MJupiter
jupiter.radius = 1.0 | units.RJupiter
jupiter.position = (-4.9829, 2.062, -0.10990) | units.AU
jupiter.velocity = (-5.158, -11.454, 0.13558) | units.kms
particles.move_to_center()
return particles
def evolve_a_single_star(m, z, model_time, algorithm=EVtwin):
"""
Code for Assignment 2A.
@param m: mass of the star.
@param z: metallicity of the star.
@param stellar: specify the stellar evolution code.
valid options are:
MESA, EVtwin (both Henyey)
SSE, SeBa (both parameterized)
@return: Dict with input parameters. mass/luminosity and runtime
"""
t_start = time()
stellar = algorithm(redirection="none")
# stellar = algorithm()
algorithm_name = str(algorithm).split('.')[-1][:-2]
stellar.parameters.metallicity = z
# stellar.commit_parameters()
# print "\nstellar.parameters:\n{0}".format(stellar.parameters)
star = Particles(mass=m)
# print "\nStar:\n{0}".format(star)
# print "\nstellar.particles:\n{0}".format(stellar.particles)
stellar.particles.add_particles(star)
channel_from_stellar = stellar.particles.new_channel_to(star)
stellar.evolve_model(model_time)
channel_from_stellar.copy()
# print "L(t=", star.age, ")=", star.luminosity, "R=", star.radius, "\n"
stellar.stop()
runtime = (time() - t_start)
set_printing_strategy("custom", preferred_units=[units.MSun, units.RSun,
units.Gyr, units.LSun], precision=4, prefix="",
separator=" [", suffix="]")
# LaTeX table/tabular output <3
print "{0} & {1} & {2} & {3} & {4} & {5} & {6} \\\\ "\
.format(algorithm_name, z, model_time, star.luminosity,
m, star.radius, runtime)
data = {}
data["algorithm_name"] = algorithm_name
data["mass"] = m
data["metallicity"] = z
data["luminosity"] = star.luminosity
data["radius"] = star.radius
data["runtime"] = runtime
#print data.items()
return data
def body_init(v1, v2, m3): # Initial condition (mass, coordinates, velocities)
particles = Particles(3)
body0 = particles[0]
body0.mass = 1.0 | nbody_system.mass
body0.position = (-1, 0., 0.) | nbody_system.length
body0.velocity = (v1, v2, 0) | nbody_system.speed
body1 = particles[1]
body1.mass = 1.0 | nbody_system.mass
body1.position = (1., 0., 0.) | nbody_system.length
body1.velocity = (v1, v2, 0.) | nbody_system.speed
body2 = particles[2]
body2.mass = m3 | nbody_system.mass
body2.position = (0., 0., 0.) | nbody_system.length
body2.velocity = (-2 * v1 / m3, -2 * v2 / m3, 0.) | nbody_system.speed
particles.move_to_center()
return particles
def body_init():
particles = Particles(3)
body0 = particles[0]
body0.mass = 1.0 | nbody_system.mass
body0.position = (-1., 0., 0.) | nbody_system.length
body0.velocity = (v1, v2, 0.) | nbody_system.speed
body1 = particles[1]
body1.mass = 1.0 | nbody_system.mass
body1.position = (1., 0., 0.) | nbody_system.length
body1.velocity = (v1, v2, 0.) | nbody_system.speed
body2 = particles[2]
body2.mass = m3 | nbody_system.mass
body2.position = (0., 0., 0.) | nbody_system.length
body2.velocity = (-2 / m3 * v1, -2 / m3 * v2, 0.) | nbody_system.speed
particles.move_to_center()
return particles
def MW_and_M31():
MW_M31 = Particles(2)
MW = MW_M31[0]
MW.mass = 1*10**6 | units.MSun
MW.position = (0,0,0) | units.kpc
MW.velocity = (0.1,0.1,0) | units.kms
M31 = MW_M31[1]
M31.mass = 1.6*10**6 | units.MSun
M31.position = (7.8,0,0) | units.kpc
M31.velocity = (0,0,0) | units.kms
return MW_M31
def sma_determinator(primary, secondary):
binary = Particles(0)
binary.add_particle(primary)
binary.add_particle(secondary)
orbital_params = get_orbital_elements_from_binary(binary, G=constants.G)
return orbital_params[2]
def sun_venus_and_earth():
particles = Particles(3)
sun = particles[0]
sun.mass = 1.0 | nbody_system.mass
#sun.radius = 1.0 | units.RSun
sun.position = (-1, 0., 0.) | nbody_system.length
sun.velocity = (v1, v2, 0) | nbody_system.speed
venus = particles[1]
venus.mass = 1.0 | nbody_system.mass
#venus.radius = 1.0 | units.RSun
venus.position = (1., 0., 0.) | nbody_system.length
venus.velocity = (v1, v2, 0.) | nbody_system.speed
earth = particles[2]
earth.mass = 0.5 | nbody_system.mass
#earth.radius = 1.0 | units.RSun
earth.position = (0., 0., 0.) | nbody_system.length
earth.velocity = (-4 * v1, -4 * v2, 0.) | nbody_system.speed
particles.move_to_center()
return particles
def sun_venus_and_earth():
particles = Particles(3)
sun = particles[0]
sun.mass = 1.0 | units.MSun
sun.position = (0.0, 0.0, 0.0) | units.m
sun.velocity = (0.0, 0.0, 0.0) | (units.m / units.s)
sun.radius = 1.0 | units.RSun
venus = particles[1]
venus.mass = 0.0025642 | units.MJupiter
venus.radius = 3026.0 | units.km
venus.position = (0.6335, 0.3499, -0.03179) | units.AU
venus.velocity = (-17.0420, 30.5055, 1.4004) | units.kms
earth = particles[2]
earth.mass = 5.9736e24 | units.kg
earth.radius = 6371.0 | units.km
earth.position = (0.2421, -0.9875, -0.00004) | units.AU
earth.velocity = (28.4468, 6.98125, 0.0002) | units.kms
particles.move_to_center()
return particles
def sun_venus_and_earth():
particles = Particles(3)
sun = particles[0]
sun.mass = 1.0 | units.MSun
sun.radius = 1.0 | units.RSun
sun.position = (855251, -804836, -3186) | units.km
sun.velocity = (7.893, 11.894, 0.20642) | (units.m / units.s)
venus = particles[1]
venus.mass = 0.0025642 | units.MJupiter
venus.radius = 3026.0 | units.km
venus.position = (-0.3767, 0.60159, 0.03930) | units.AU
venus.velocity = (-29.7725, -18.849, 0.795) | units.kms
earth = particles[2]
earth.mass = 1.0 | units.MEarth
earth.radius = 1.0 | units.REarth
earth.position = (-0.98561, 0.0762, -7.847e-5) | units.AU
earth.velocity = (-2.927, -29.803, -0.0005327) | units.kms
particles.move_to_center()
return particles
def sun_venus_and_earth():
particles = Particles(3)
sun = particles[0]
sun.mass = 1.0 | units.kg
#sun.radius = 1e-2 | units.m
sun.position = (-1, 0, 0) | units.m
sun.velocity = (v1, v2, 0) | (units.m / units.s)
venus = particles[1]
venus.mass = 1.0 | units.kg
#venus.radius = 1e-2 | units.m
venus.position = (1, 0, 0) | units.m
venus.velocity = (v1, v2, 0) | (units.m / units.s)
earth = particles[2]
earth.mass = 0.5 | units.kg
#earth.radius = 1e-2 | units.m
earth.position = (0, 0, 0) | units.m
earth.velocity = (-4 * v1, -4 * v2, 0) | (units.m / units.s)
particles.move_to_center()
return particles
def new_system():
particles = Particles(3)
sun = particles[0]
sun.mass = 1.0 | units.MSun
sun.radius = 1.0 | units.REarth
sun.position = (1, 0, 0) | units.AU
sun.velocity = (0, 0, 20) | units.kms
venus = particles[1]
venus.mass = 1.0 | units.MSun
venus.radius = 1.0 | units.REarth
venus.position = (0, -1, 0) | units.AU
venus.velocity = (20, 0, 0) | units.kms
earth = particles[2]
earth.mass = 1.0 | units.MSun
earth.radius = 1.0 | units.REarth
earth.position = (0, 0, -1) | units.AU
earth.velocity = (0, 20, 0) | units.kms
particles.move_to_center()
return particles
def sun_venus_and_earth():
particles = Particles(3)
sun = particles[0]
sun.mass = 1.0 | units.MSun
sun.position = (0.0,0.0,0.0) | units.m
sun.velocity = (0.0,0.0,0.0) | (units.m/units.s)
sun.radius = 1.0 | units.RSun
venus = particles[1]
venus.mass = 0.0025642 | units.MJupiter
venus.radius = 3026.0 | units.km
venus.position = (0.6335, 0.3499, -0.03179) | units.AU
venus.velocity = (-17.0420, 30.5055, 1.4004) | units.kms
earth = particles[2]
earth.mass = 5.9736e24 | units.kg
earth.radius = 6371.0 | units.km
earth.position = (0.2421, -0.9875, -0.00004) | units.AU
earth.velocity = (28.4468, 6.98125, 0.0002) | units.kms
particles.move_to_center()
return particles
def sun_venus_and_earth():
particles = Particles(3)
sun = particles[0]
sun.mass = 1.0 | units.MSun
sun.radius = 1.0 | units.RSun
sun.position = (855251, -804836, -3186) |units.km
sun.velocity = (7.893, 11.894, 0.20642) | (units.m/units.s)
venus = particles[1]
venus.mass = 0.0025642 | units.MJupiter
venus.radius = 3026.0 | units.km
venus.position = (-0.3767, 0.60159, 0.03930) | units.AU
venus.velocity = (-29.7725, -18.849, 0.795) | units.kms
earth = particles[2]
earth.mass = 1.0 | units.MEarth
earth.radius = 1.0 | units.REarth
earth.position = (-0.98561, 0.0762, -7.847e-5) | units.AU
earth.velocity = (-2.927, -29.803, -0.0005327) | units.kms
particles.move_to_center()
return particles
def evolve_sun_jupiter(particles, tend, dt):
SunJupiter = Particles()
SunJupiter.add_particle(particles[0])
SunJupiter.add_particle(particles[1])
converter = nbody_system.nbody_to_si(particles.mass.sum(),
particles[1].position.length())
gravity = ph4(converter)
gravity.particles.add_particles(particles)
channel_from_to_SunJupiter = gravity.particles.new_channel_to(SunJupiter)
semi_major_axis = []
eccentricity = []
times = quantities.arange(0 | units.yr, tend, dt)
for i, t in enumerate(times):
print "Time=", t.in_(units.yr)
channel_from_to_SunJupiter.copy()
orbital_elements = orbital_elements_from_binary(SunJupiter,
G=constants.G)
a = orbital_elements[2]
e = orbital_elements[3]
semi_major_axis.append(a.value_in(units.AU))
eccentricity.append(e)
gravity.evolve_model(t, timestep=dt)
# Plot
fig = plt.figure(figsize=(8, 6))
ax1 = fig.add_subplot(211,
xlabel='time(yr)',
ylabel='semi major axis (AU)')
ax1.plot(times.value_in(units.yr), semi_major_axis)
ax2 = fig.add_subplot(212, xlabel='time(yr)', ylabel='eccentriity')
ax2.plot(times.value_in(units.yr), eccentricity)
plt.show()
gravity.stop()
def evolve_sun_jupiter(particles, tend, dt):
SunJupiter = Particles()
SunJupiter.add_particle(particles[0])
SunJupiter.add_particle(particles[1])
converter=nbody_system.nbody_to_si(particles.mass.sum(), particles[1].position.length())
gravity = ph4(converter)
gravity.particles.add_particles(particles)
channel_from_to_SunJupiter = gravity.particles.new_channel_to(SunJupiter)
semi_major_axis = list()
eccentricity = list()
times = quantities.arange(0|units.yr, tend+dt, dt)
for i,t in enumerate(times):
#print "Time =", t.in_(units.yr)
channel_from_to_SunJupiter.copy()
orbital_elements = orbital_elements_from_binary(SunJupiter, G=constants.G)
a = orbital_elements[2]
e = orbital_elements[3]
semi_major_axis.append(a.value_in(units.AU))
eccentricity.append(e)
gravity.evolve_model(t, timestep=dt)
gravity.stop()
# save the data: times, semi_major_axis and eccentricity of Jupiter's orbit
t_a_e = np.column_stack((times.value_in(units.yr), semi_major_axis, eccentricity))
np.savetxt('t_a_e.txt', t_a_e, delimiter=',')
# make plots
fig = plt.figure(figsize = (8, 6))
ax1 = fig.add_subplot(211, xlabel = 'time(yr)', ylabel = 'semi major axis (AU)')
ax1.plot(times.value_in(units.yr), semi_major_axis)
ax2 = fig.add_subplot(212, xlabel = 'time(yr)', ylabel = 'eccentriity')
ax2.plot(times.value_in(units.yr), eccentricity)
plt.show()
def add_comet_objects(pre_tack_giants_system, N_objects, comet_positions,
comet_velocities):
for i in tqdm(range(N_objects)):
comet = Particles(1)
comet.name = "OORT_" + str(i)
comet.mass = 0.0 | units.MSun #Take massless test particles
comet.radius = 0.0 | units.RSun
comet.position = (comet_positions[i, 0], comet_positions[i, 1],
comet_positions[i, 2])
comet.velocity = (comet_velocities[i, 0], comet_velocities[i, 1],
comet_velocities[i, 2])
comet.density = 0.0 | (units.MSun / (units.RSun**3))
pre_tack_giants_system.add_particle(comet)
return pre_tack_giants_system
def merge_two_particles(gravity, particles_in_encounter):
new_particle = Particles(1)
new_particle.mass = particles_in_encounter.total_mass()
new_particle.position = particles_in_encounter.center_of_mass()
new_particle.velosity = particles_in_encounter.center_of_mass_velocity()
new_particle.radius = particles_in_encounter.radius.sum()
gravity.particles.add_particles(new_particle)
gravity.particles.remove_particles(particles_in_encounter)
def MW():
MW = Particles(1 + N1)
MW1 = MW[0]
MW1.mass = 1 * 10**11 | units.MSun
MW1.position = (0, 0, 0) | units.kpc
MW1.velocity = (10, 10, 0) | units.kms
#MW.u = 0.5*(math.sqrt(2)*10)**2*1000*1000 | units.m**2 * units.s**-2
for i in range(N1):
MW[1 + i].mass = 10 | units.MSun
angle = random.random() * 2 * math.pi
MW[1 + i].position = (r * math.cos(angle), r * math.sin(angle),
0) | units.kpc
MW[1 + i].velocity = (10 + v * math.sin(angle),
10 - math.cos(angle) * v, 0) | units.kms
return MW
def add_comet_objects(system, N_objects, rand_pos, rand_vel):
for i in tqdm(range(N_objects)):
oort = Particles(1)
oort.name = "OORT_" + str(i)
oort.mass = 0.0 | units.MSun
oort.radius = (2.3 | units.km).in_(units.RSun) # This is purely non-zero for collisional purposes
oort.position = (rand_pos[i, 0], rand_pos[i, 1], rand_pos[i, 2])
oort.velocity = (rand_vel[i, 0], rand_vel[i, 1], rand_vel[i, 2])
system.add_particle(oort)
for particle in system: #So that Mercury will work
particle.density = 3*particle.mass/(4*np.pi*particle.radius**3)
return system
def new_system():
stars = Particles(3)
sun = stars[0]
sun.mass = units.MSun(1.0)
sun.position = units.m(np.array((0.0,0.0,0.0)))
sun.velocity = units.ms(np.array((0.0,0.0,0.0)))
sun.radius = units.RSun(1.0)
earth = stars[1]
earth.mass = units.kg(5.9736e24)
earth.radius = units.km(6371)
earth.position = units.km(np.array((149.5e6,0.0,0.0)))
earth.velocity = units.ms(np.array((0.0,29800,0.0)))
moon = stars[2]
moon.mass = units.kg(7.3477e22 )
moon.radius = units.km(1737.10)
moon.position = units.km(np.array((149.5e6 + 384399.0 ,0.0,0.0)))
moon.velocity = ([0.0,1.022,0] | units.km/units.s) + earth.velocity
return stars
def get_ps_from_yt(pltfile, particle_type="all"):
"""Take a FLASH plotfile and return an AMUSE
particle set.
Keyword arguments:
pltfile -- The FLASH hdf5 plot or checkpoint file.
Note a plotfile means there must also be
a particle file with the same ID number.
particle_type -- the type of particle that you
want from FLASH. Can be:
star -- active FLASH particle type
sink -- sink FLASH particle type
any other string or none returns
all particle types.
The default is all
Returns:
stars -- An AMUSE particle set.
"""
import yt
ds = yt.load(pltfile)
dd = ds.all_data()
all_parts_mass = dd['particle_mass'].in_units('Msun')
all_parts_pos = dd['particle_position'].in_units('cm')
all_parts_vel = dd['particle_velocity'].in_units('cm/s')
if (particle_type == 'star' or particle_type == 'stars'):
# Index for only the star particles, and not including sink particles.
mass_ind = np.where(dd['particle_type'].v == 1)
elif (particle_type == 'sink' or particle_type == 'sinks'):
mass_ind = np.where(dd['particle_type'].v == 2)
else:
mass_ind = np.arange(len(all_parts_mass))
all_parts_mass = all_parts_mass[mass_ind]
all_parts_pos = all_parts_pos[mass_ind]
all_parts_vel = all_parts_vel[mass_ind]
num_parts = len(all_parts_mass.v)
stars = Particles(num_parts)
stars.mass = all_parts_mass.v | u.MSun
stars.position = all_parts_pos.v | u.cm
stars.velocity = all_parts_vel.v | u.cm/u.s
stars.index_of_the_particle = range(num_parts)
return stars
def merge_two_bodies(bodies, particles_in_encounter):
com_pos = particles_in_encounter.center_of_mass()
com_vel = particles_in_encounter.center_of_mass_velocity()
d = (particles_in_encounter[0].position - particles_in_encounter[1].position)
v = (particles_in_encounter[0].velocity - particles_in_encounter[1].velocity)
print("Actually merger occurred:")
print("Two objects (M=",particles_in_encounter.mass.in_(units.MSun),
") collided with d=", d.length().in_(units.au))
#time.sleep(10)
new_particle=Particles(1)
new_particle.mass = particles_in_encounter.total_mass()
new_particle.position = com_pos
new_particle.velocity = com_vel
new_particle.radius = ((particles_in_encounter.radius**3).sum())**(1./3.) # New radius cannot simply be summed
bodies.add_particles(new_particle)
bodies.remove_particles(particles_in_encounter)
def new_field_stars(
N,
width=10 | units.parsec,
height=10 | units.parsec,
depth=100 | units.parsec,
massdistribution="salpeter",
agespread=3 | units.Gyr,
seed=1701,
):
np.random.seed(seed)
stars = Particles(N)
stars.x = (np.random.random(N) - 0.5) * width
stars.y = (np.random.random(N) - 0.5) * height
stars.z = (np.random.random(N) - 0.02) * depth
if massdistribution == "salpeter":
stars.mass = new_salpeter_mass_distribution(N)
return stars