orbital_evolution.binary module

Class Inheritance Diagram

Define a class for binaries which can be evolved.

class orbital_evolution.binary.Binary(primary, secondary, *, disk_lock_frequency, disk_dissipation_age, initial_semimajor=None, initial_orbital_period=None, initial_eccentricity=0.0, initial_inclination=0.0, secondary_formation_age=None)

Bases: object

A class for binaries POET can evolve.

__init__(primary, secondary, *, disk_lock_frequency, disk_dissipation_age, initial_semimajor=None, initial_orbital_period=None, initial_eccentricity=0.0, initial_inclination=0.0, secondary_formation_age=None)

Create a binary system out of two bodies.

Parameters:

• primary (-) – The first body in the system. Assumed to always be there, so for a star-planet system this should be the star.
• secondary (-) – The second body in the system, initially may not be there and later may be engulfed by the first body.
• disk_lock_frequency (-) – Frequency of the surface spin of the primary when disk is present in rad/day.
• disk_dissipation_age (-) – Age when disk dissipates in Gyrs.
• initial_semimajor (-) – The semimajor axis of the orbit at which the secondary forms in solar radii. If omitted, initial_orbital_period must be specified.
• initial_orbital_period (-) – Alternative to specifying the initial semimajor axis.
• initial_eccentricity (-) – The eccentricity of the orbit at which the secondary forms.
• initial_inclination (-) – Inclination between surface zone of primary and initial orbit in radians.
• secondary_formation_age (-) – Age when the secondary forms.

Returns: None

_create_c_code(c_code_fname, *, final_age, max_time_step, precision, eccentricity_expansion_fname)

Create a c++ file calculating the currently set-up evolution.

_get_evolution_quantities()

Return the list of quantities in the evolution of the binary.

Parameters:None – Returns:A list of the evolution quantities tracked for an evolution of the current system. Return type:[str]

_get_required_age_indices(evolution_ages)

Return the indices within evolution_ages of self._required_ages.

configure(*, age, semimajor, eccentricity, spin_angmom, inclination, periapsis, evolution_mode)

Set the current state (orbit) of a system.

Parameters:

• age (-) – The age to set the system to.
• semimajor (-) – The semimajor axis of the orbit in solar radii.
• eccentricity (-) – The eccentricity of the orbit.
• spin_angmom (-) – The spin angular momenta of the zones of the bodies (body 1 first, outermost zone to innermost, followed by body 2).
• inclination (-) – The inclinations of the zones of the bodies (same order as spin_angmom). The surface zone inclination must be omitted for single body systems.
• periapsis (-) – The arguments of periapsis of the zones of the bodies (same order as spin_angmom, but not including the surface zone of the first body).
• evolution_mode (-) – The evolution mode to assume. Must be one of the constants defined.

Returns: None

delete()

Destroy the binary created at construction.

evolution_modes = ['LOCKED_SURFACE_SPIN', 'BINARY', 'SINGLE', 'TABULATION']

static evolution_quantity_c_type(quantity)

Return the ctypes type of the given evolution quantity.

evolve(final_age, max_time_step, precision, required_ages, *, print_progress=False, create_c_code='', eccentricity_expansion_fname=None, timeout=0, max_time_steps=0)

Evolve the system forward from its current state.

Parameters:

• final_age (-) – The age at which to stop the evolution in Gyrs. The starting age must be already set for the system through configure.
• max_time_step (-) – The maximum size of the time step allowed in Gyrs.
• precision (-) – The precision to require of the solution.
• required_ages (-) – Ages at which the evolution must stop precisely.
• print_progress (-) – Should output be created to show the progress in time steps.
• create_c_code (-) – The name of a file to create which when compiled will calculate the exact evolution currently set-up for this binary. If empty, no such file is created.
• eccentricity_expansion_fname (-) – The filename from which eccentricity expansion coefficients were read. Only used if create_c_code is not empty.
• timeout (-) – The maximum number of seconds the evolution is allowed to run. Non-positive value results in no timeout. Partially cumputed evolutions that time out can still be querried.
• max_time_steps (-) – The maximum number of time steps the evolution is allowed to take (also includes the current set of discarded steps).

Returnns: None

final_state()

Return the final evolution state of a system (all quantities).

get_evolution(quantities=None, required_ages_only=False)

Return the last calculated evolution.

Parameters:

• quantities – An iterable of quantities to read the evolution of. The evolution of omitted quantities can still be obtained later by subsequent calls to this method. The allowed entries are in the star_star_evolution_quantities for binary star systems or in star_planet_evolution_quantities for a star-planet system. If None, it defaults to the full list of quantities for the given system.
• required_ages_only (bool) – If True, the evolution returned contains only the values of the quantities at the required_ages specified when evolve() was called.

Returns:

A structure with mebers named the same way as the input list of quantities containing the values of the corresponding quantity at each evolution step. The order is always in increasing age.

Return type:

Sturture

orbital_angular_momentum(semimajor, eccentricity)

The orbital agular momentum for the given semimajor/eccentricity.

Parameters:

• semimajor (-) – The semimajor axis of the system.
• eccentricity (-) – The orbital eccentricity.

Returns:

The orbital angular momentum if the two bodies are in an orbit with the given semimajor axis and eccentricity in solar units.

orbital_frequency(semimajor)

The orbital frequency of the system for the given semimajor axis.

Parameters:semimajor (-) – The semimajor axis at which the system’s orbital period is required in solar radii. Returns:The orbital period in days if the two bodies of this system are in an orbit with the given semimajor axis.

orbital_period(semimajor)

The orbital period of the system for the given semimajor axis.

Parameters:semimajor (-) – The semimajor axis at which the system’s orbital period is required in solar radii. Returns:The orbital period in days if the two bodies of this system are in an orbit with the given semimajor axis.

semimajor(orbital_period)

The semimajor axis of the system for the given orbital period.

Parameters:orbital_period (-) – The orbital period at which the system’s orbital period is required in days. Returns:The semimajor axis in solar radii if the two bodies of this system are in an orbit with the given period.