def get_planetary_systems_from_set(bodies,
converter=None,
RelativePosition=False):
# Initialize Kepler
if converter == None:
converter = nbody_system.nbody_to_si(
bodies.mass.sum(),
2 * np.max(bodies.radius.number) | bodies.radius.unit)
kep_p = Kepler(unit_converter=converter, redirection='none')
kep_p.initialize_code()
kep_s = Kepler(unit_converter=converter, redirection='none')
kep_s.initialize_code()
# Seperate Out Planets and Stars from Bodies
stars, planets = util.get_stars(bodies), util.get_planets(bodies)
num_stars, num_planets = len(stars), len(planets)
# Initialize the Dictionary that Contains all Planetary Systems
systems = {}
# Start Looping Through Stars to Find Bound Planets
for star in stars:
system_id = star.id
#star.semimajor_axis, star.eccentricity, star.period, star.true_anomaly, star.mean_anomaly, star.kep_energy, star.angular_momentum = \
# None, None, None, None, None, None, None
current_system = systems.setdefault(system_id, Particles())
current_system.add_particle(star)
for planet in planets:
total_mass = star.mass + planet.mass
kep_pos = star.position - planet.position
kep_vel = star.velocity - planet.velocity
kep_p.initialize_from_dyn(total_mass, kep_pos[0], kep_pos[1],
kep_pos[2], kep_vel[0], kep_vel[1],
kep_vel[2])
a_p, e_p = kep_p.get_elements()
if e_p < 1.0:
# Check to See if The Stellar System is a Binary
# Note: Things get complicated if it is ...
noStellarHeirarchy = False
for other_star in (stars - star):
kep_s.initialize_from_dyn(
star.mass + other_star.mass, star.x - other_star.x,
star.y - other_star.y, star.z - other_star.z,
star.vx - other_star.vx, star.vy - other_star.vy,
star.vz - other_star.vz)
a_s, e_s = kep_s.get_elements()
r_apo = kep_s.get_apastron()
HillR = util.calc_HillRadius(a_s, e_s, other_star.mass,
star.mass)
if e_s >= 1.0 or HillR < r_apo:
noStellarHeirarchy = True
else:
noStellarHeirarchy = False
if noStellarHeirarchy:
# Get Additional Information on Orbit
planet.semimajor_axis = a_p
planet.eccentricity = e_p
planet.period = kep_p.get_period()
planet.true_anomaly, planet.mean_anomaly = kep_p.get_angles(
)
#planet.kep_energy, planet.angular_momentum = kep_p.get_integrals()
# Add the Planet to the System Set
current_system.add_particle(planet)
else:
# Handling for Planetary Systems in Stellar Heirarchical Structures
# Note: This is empty for now, maybe consider doing it by the heaviest bound stellar object as the primary.
pass
else:
continue
kep_p.stop()
kep_s.stop()
return systems
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
