def merge_two_stars(bodies, particles_in_encounter):
"""
Merge two stars into one
"""
com_pos = particles_in_encounter.center_of_mass()
com_vel = particles_in_encounter.center_of_mass_velocity()
star_0 = particles_in_encounter[0]
star_1 = particles_in_encounter[1]
new_particle = Particles(1)
new_particle.birth_age = particles_in_encounter.birth_age.min()
new_particle.mass = particles_in_encounter.total_mass()
new_particle.age = min(particles_in_encounter.age) \
* max(particles_in_encounter.mass)/new_particle.mass
new_particle.position = com_pos
new_particle.velocity = com_vel
new_particle.name = "Star"
new_particle.radius = particles_in_encounter.radius.max()
print("# old radius:", particles_in_encounter.radius.in_(units.AU))
print("# new radius:", new_particle.radius.in_(units.AU))
bodies.add_particles(new_particle)
print("# Two stars (M=", particles_in_encounter.mass.in_(units.MSun),
") collided at d=",
(star_0.position - star_1.position).length().in_(units.AU))
bodies.remove_particles(particles_in_encounter)
def resolve_sinks(self):
print "processing high dens particles...",
highdens=self.gas_particles.select_array(lambda rho:rho>self.density_threshold,["rho"])
print "N=", len(highdens)
candidate_stars=highdens.copy()
self.gas_particles.remove_particles(highdens)
self.gas_particles.synchronize_to(self.code.gas_particles)
print "new sinks..."
if len(candidate_stars)>0: # had to make some changes to prevent double adding particles
print "Adding stars, N=", len(candidate_stars)
newstars_in_code = self.code.dm_particles.add_particles(candidate_stars)
newstars = Particles()
for nsi in newstars_in_code:
if nsi not in self.star_particles:
newstars.add_particle(nsi)
else:
print "this star should not exicst"
newstars.name = "Star"
newstars.birth_age = self.code.model_time
newstars.Lx = 0 | (units.g * units.m**2)/units.s
newstars.Ly = 0 | (units.g * units.m**2)/units.s
newstars.Lz = 0 | (units.g * units.m**2)/units.s
print "pre N=", len(self.star_particles), len(newstars), len(self.code.dm_particles)
#self.star_particles.add_sinks(newstars)
self.star_particles.add_particles(newstars)
print "post N=", len(self.star_particles), len(newstars), len(self.code.dm_particles)
else:
print "N candidates:", len(candidate_stars)
def merge_two_stars(bodies, particles_in_encounter):
com_pos = particles_in_encounter.center_of_mass()
com_vel = particles_in_encounter.center_of_mass_velocity()
new_particle=Particles(1)
mu = particles_in_encounter[0].mass/particles_in_encounter.mass.sum()
new_particle.birth_age = particles_in_encounter.birth_age.min()
new_particle.mass = particles_in_encounter.total_mass()
new_particle.position = com_pos
new_particle.velocity = com_vel
new_particle.name = "Star"
new_particle.radius = particles_in_encounter.radius.max()
print "old radius:", particles_in_encounter.radius.value_in(units.AU)
print "new radius:", new_particle.radius.value_in(units.AU)
bodies.add_particles(new_particle)
print "Two stars (M=",particles_in_encounter.mass,") collided at d=", com_pos.length()
bodies.remove_particles(particles_in_encounter)
def merge_two_stars(bodies, particles_in_encounter):
com_pos = particles_in_encounter.center_of_mass()
com_vel = particles_in_encounter.center_of_mass_velocity()
new_particle = Particles(1)
mu = particles_in_encounter[0].mass / particles_in_encounter.mass.sum()
new_particle.birth_age = particles_in_encounter.birth_age.min()
new_particle.mass = particles_in_encounter.total_mass()
new_particle.position = com_pos
new_particle.velocity = com_vel
new_particle.name = "Star"
new_particle.radius = particles_in_encounter.radius.max()
print("old radius:", particles_in_encounter.radius.value_in(units.AU))
print("new radius:", new_particle.radius.value_in(units.AU))
bodies.add_particles(new_particle)
print("Two stars (M=", particles_in_encounter.mass, ") collided at d=",
com_pos.length())
bodies.remove_particles(particles_in_encounter)
def resolve_sinks(self):
print("processing high dens particles...", end=' ')
highdens = self.gas_particles.select_array(
lambda rho: rho > self.density_threshold, ["rho"])
print("N=", len(highdens))
candidate_stars = highdens.copy()
self.gas_particles.remove_particles(highdens)
self.gas_particles.synchronize_to(self.code.gas_particles)
print("new sinks...")
if len(
candidate_stars
) > 0: # had to make some changes to prevent double adding particles
print("Adding stars, N=", len(candidate_stars))
newstars_in_code = self.code.dm_particles.add_particles(
candidate_stars)
newstars = Particles()
for nsi in newstars_in_code:
if nsi not in self.star_particles:
newstars.add_particle(nsi)
else:
print("this star should not exicst")
newstars.name = "Star"
newstars.birth_age = self.code.model_time
newstars.Lx = 0 | (units.g * units.m**2) / units.s
newstars.Ly = 0 | (units.g * units.m**2) / units.s
newstars.Lz = 0 | (units.g * units.m**2) / units.s
print("pre N=", len(self.star_particles), len(newstars),
len(self.code.dm_particles))
# self.star_particles.add_sinks(newstars)
self.star_particles.add_particles(newstars)
print("post N=", len(self.star_particles), len(newstars),
len(self.code.dm_particles))
else:
print("N candidates:", len(candidate_stars))
