def _posvel(star_mass, planet_mass, a):
zeros = posidonius.Axes(0., 0., 0.)
#////////// Specify initial position and velocity for a stable orbit
#////// Keplerian orbital elements, in the `asteroidal' format of Mercury code
#a = 0.018; # semi-major axis (in AU)
e = 0.1
# eccentricity
i = 5. * posidonius.constants.DEG2RAD
# inclination (degrees)
p = 0. * posidonius.constants.DEG2RAD
# argument of pericentre (degrees)
n = 0. * posidonius.constants.DEG2RAD
# longitude of the ascending node (degrees)
l = 0. * posidonius.constants.DEG2RAD
# mean anomaly (degrees)
p = (p + n)
# Convert to longitude of perihelion !!
q = a * (1.0 - e)
# perihelion distance
position, velocity = posidonius.calculate_cartesian_coordinates(
planet_mass,
q,
e,
i,
p,
n,
l,
masses=[star_mass],
positions=[zeros],
velocities=[zeros])
return position, velocity
p = 0. * posidonius.constants.DEG2RAD
# argument of pericentre (degrees)
n = 0. * posidonius.constants.DEG2RAD
# longitude of the ascending node (degrees)
l = 0. * posidonius.constants.DEG2RAD
# mean anomaly (degrees)
p = (p + n)
# Convert to longitude of perihelion !!
q = a * (1.0 - e)
# perihelion distance
planet_position, planet_velocity = posidonius.calculate_cartesian_coordinates(
planet_mass,
q,
e,
i,
p,
n,
l,
masses=[star_mass],
positions=[star_position],
velocities=[star_velocity])
#////// Initialization of planetary spin
planet_obliquity = 40.10704565915762 * posidonius.constants.DEG2RAD # 0.2 rad
planet_rotation_period = 240. # hours
planet_angular_frequency = posidonius.constants.TWO_PI / (
planet_rotation_period / 24.) # days^-1
# Pseudo-synchronization period
#planet_keplerian_orbital_elements = posidonius.calculate_keplerian_orbital_elements(planet_mass, planet_position, planet_velocity, masses=[star_mass], positions=[star_position], velocities=[star_velocity])
#planet_semi_major_axis = planet_keplerian_orbital_elements[0]
#planet_eccentricity = planet_keplerian_orbital_elements[2]
p = 0. * posidonius.constants.DEG2RAD
# argument of pericentre (degrees)
n = 0. * posidonius.constants.DEG2RAD
# longitude of the ascending node (degrees)
l = 0. * posidonius.constants.DEG2RAD
# mean anomaly (degrees)
p = (p + n)
# Convert to longitude of perihelion !!
q = a * (1.0 - e)
# perihelion distance
star2_position, star2_velocity = posidonius.calculate_cartesian_coordinates(
star2_mass,
q,
e,
i,
p,
n,
l,
masses=[star1_mass],
positions=[star1_position],
velocities=[star1_velocity])
#////// Initialization of star2ary spin
star2_obliquity = 5.0 * posidonius.constants.DEG2RAD # 0.2 rad
star2_rotation_period = 70. # hours
star2_angular_frequency = posidonius.constants.TWO_PI / (
star2_rotation_period / 24.) # days^-1
# Pseudo-synchronization period
#star2_keplerian_orbital_elements = posidonius.calculate_keplerian_orbital_elements(star2_mass, star2_position, star2_velocity, masses=[star1_mass], positions=[star1_position], velocities=[star1_velocity])
#star2_semi_major_axis = star2_keplerian_orbital_elements[0]
#star2_eccentricity = star2_keplerian_orbital_elements[2]
