def get_bodies_in_orbit(m0, m_ffp, m_bp, a_bp, e_bp, phi_bp, inc_bp, lan_bp, b_ffp, r_inf):
#Bodies
bodies = Particles()
##Get BP in orbit
#Binary
star_planet = new_binary_from_orbital_elements(m0, m_bp, a_bp, e_bp, true_anomaly=phi_bp, inclination = inc_bp, longitude_of_the_ascending_node = lan_bp)
#Planet attributes
star_planet.eccentricity = e_bp
star_planet.semimajoraxis = a_bp
#Center on the star
star_planet.position -= star_planet[0].position
star_planet.velocity -= star_planet[0].velocity
cm_p = star_planet.center_of_mass()
cm_v = star_planet.center_of_mass_velocity()
##Get FFP in orbit
#Particle set
m0_ffp = Particles(2)
#Zeros and parabolic velocity
zero_p = 0.0 | nbody_system.length
zero_v = 0.0 | nbody_system.speed
parabolic_velocity = get_parabolic_velocity(m0, m_bp, b_ffp, r_inf)
#Central star
m0_ffp[0].mass = m0
m0_ffp[0].position = (zero_p,zero_p,zero_p)
m0_ffp[0].velocity = (zero_v,zero_v,zero_v)
#Free-floating planet
m0_ffp[1].mass = m_ffp
m0_ffp[1].position = (-r_inf+cm_p[0], b_ffp+cm_p[1], cm_p[2])
m0_ffp[1].velocity = (parabolic_velocity+cm_v[0], cm_v[1], cm_v[2])
#To find the orbital period of the BP
G = (1.0 | nbody_system.length**3 * nbody_system.time**-2 * nbody_system.mass**-1)
orbital_period_bp = 2*math.pi*((a_bp**3)/(G*m0)).sqrt()
#To find the distance and time to periastron
kep = Kepler()
kep.initialize_code()
star_planet_as_one = Particles(1)
star_planet_as_one.mass = m0 + m_bp
star_planet_as_one.position = cm_p
star_planet_as_one.velocity = cm_v
kepler_bodies = Particles()
kepler_bodies.add_particle(star_planet_as_one[0])
kepler_bodies.add_particle(m0_ffp[1])
kep.initialize_from_particles(kepler_bodies)
kep.advance_to_periastron()
time_pericenter = kep.get_time()
kep.stop()
binary = [star_planet_as_one[0], m0_ffp[1]]
sma, e, inclination, long_asc_node, arg_per = my_orbital_elements_from_binary(binary)
m0_ffp.eccentricity = e
m0_ffp.semimajoraxis = sma
#Adding bodies. Order: star, ffp, bp
bodies.add_particle(m0_ffp[0])
bodies.add_particle(m0_ffp[1])
bodies.add_particle(star_planet[1])
return bodies, time_pericenter, orbital_period_bp
sun_and_stone = Particles(2)
sun_and_stone[0].position = [-5.40085336308e+13, -5.92288255636e+13, 0.
] | units.m
sun_and_stone[0].velocity = [-68.4281023588, -90.213640012, 0.
] | (units.m / units.s)
sun_and_stone[0].mass = 1.98892e+30 | units.kg
sun_and_stone[1].position = [2.31421952844e+17, 1.72742642121e+17, 0.
] | units.m
sun_and_stone[1].velocity = [500794.477878, 373808.365427, 0.
] | (units.m / units.s)
sun_and_stone[1].mass = 0. | units.kg
print " particles:"
print sun_and_stone
converter = nbody_system.nbody_to_si(1 | units.MSun, 1 | units.AU)
kepler = Kepler(converter)
kepler.initialize_code()
kepler.initialize_from_particles(sun_and_stone)
semi, ecc = kepler.get_elements()
apo = kepler.get_apastron()
per = kepler.get_periastron()
period = kepler.get_period()
kepler.stop()
print " semi-major axis ", semi.in_(units.AU)
print " eccentricity ", ecc
print " apocenter ", apo.in_(units.AU)
print " pericenter ", per.in_(units.AU)
print " period", period
