galpy.potential.Potential.rtide

Potential.rtide(R, z, phi=0.0, t=0.0, M=None)

Calculate the tidal radius for object of mass M assuming a circular orbit

Parameters:

• R (float or Quantity) – Galactocentric radius

• z (float or Quantity) – height

• phi (float or Quantity, optional) – azimuth (default: 0.0)

• t (float or Quantity, optional) – time (default: 0.0)

• M (float or Quantity) – mass of the object

Returns:

Tidal radius

Return type:

float or Quantity

Notes

• 2018-03-21 - Written - Webb (UofT)

• The tidal radius is computed as

  \[r_t^3 = \frac{GM_s}{\Omega^2-\mathrm{d}^2\Phi/\mathrm{d}r^2}\]

  where \(M_s\) is the cluster mass, \(\Omega\) is the circular frequency, and \(\Phi\) is the gravitational potential. For non-spherical potentials, we evaluate \(\Omega^2 = (1/r)(\mathrm{d}\Phi/\mathrm{d}r)\) and evaluate the derivatives at the given position of the cluster.