hyperion.densities.PowerLawEnvelope

class hyperion.densities.PowerLawEnvelope

This class implements the density structure for a spherically symmetric power-law envelope, with a density given by:

\rho(r) = \rho_0^{\rm env}\,\left(\frac{r}{r_0}\right)^\gamma \\

Once the PowerLawEnvelope class has been instantiated, the parameters for the density structure can be set via attributes:

>>> from hyperion.util.constants import msun, au, pc
>>> from hyperion.densities.power_law_envelope import PowerLawEnvelope
>>> envelope = PowerLawEnvelope()
>>> envelope.mass = msun
>>> envelope.rmin = 0.1 * au
>>> envelope.rmax = pc

PowerLawEnvelope instances can only be used with spherical polar grids at this time.

Attributes

mass total mass (g)
rho_0 density at r_0 (g/cm^3)
r_0 radius at which rho_0 is defined (cm)
rmax outer radius (cm)
rmin inner radius (cm)
power density power-law exponent
dust dust properties (filename or dust object)

Methods

density(grid[, ignore_cavity]) Return the density grid
outermost_radius(rho) Find the outermost radius at which the density of the envelope has fallen to rho.
midplane_cumulative_density(r) Find the cumulative column density as a function of radius.
add_bipolar_cavity() Add a bipolar cavity to the envelope.

Methods (detail)

density(grid, ignore_cavity=False)

Return the density grid

Parameters:
grid : SphericalPolarGrid or CylindricalPolarGrid instance.

The spherical polar grid object containing information about the position of the grid cells.
Returns:
rho : np.ndarray

A 3-dimensional array containing the density of the envelope inside each cell. The shape of this array is the same as grid.shape.
outermost_radius(rho)

Find the outermost radius at which the density of the envelope has fallen to rho.

Parameters:
rho : float

The density for which to determine the radius
Returns:
r : float

The radius at which the density has fallen to rho
midplane_cumulative_density(r)

Find the cumulative column density as a function of radius.

The cumulative density is measured outwards from the origin, and in the midplane.

Parameters:
r : np.ndarray

Array of values of the radius up to which to tabulate the cumulative density.
Returns:
rho : np.ndarray

Array of values of the cumulative density.
add_bipolar_cavity()

Add a bipolar cavity to the envelope.

Returns:
cavity : BipolarCavity instance

The bipolar cavity instance, which can then be used to set the parameters of the cavity.