Softened-needle bar potential¶
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class
galpy.potential.
SoftenedNeedleBarPotential
(amp=1.0, a=4.0, b=0.0, c=1.0, normalize=False, pa=0.4, omegab=1.8, ro=None, vo=None)[source]¶ Class that implements the softened needle bar potential from Long & Murali (1992)
\[\Phi(x,y,z) = \frac{\mathrm{amp}}{2a}\,\ln\left(\frac{x-a+T_-}{x+a+T_+}\right)\]where
\[T_{\pm} = \sqrt{(a\pm x)^2 + y^2+(b+\sqrt{z^2+c^2})^2}\]For a prolate bar, set \(b\) to zero.
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__init__
(amp=1.0, a=4.0, b=0.0, c=1.0, normalize=False, pa=0.4, omegab=1.8, ro=None, vo=None)[source]¶ NAME:
__init__PURPOSE:
initialize a softened-needle bar potentialINPUT:
amp - amplitude to be applied to the potential (default: 1); can be a Quantity with units of mass
a= (4.) Bar half-length (can be Quantity)
b= (1.) Triaxial softening length (can be Quantity)
c= (1.) Prolate softening length (can be Quantity)
pa= (0.4) The position angle of the x axis (rad or Quantity)
omegab= (1.8) Pattern speed (can be Quantity)
normalize - if True, normalize such that vc(1.,0.)=1., or, if given as a number, such that the force is this fraction of the force necessary to make vc(1.,0.)=1.
ro=, vo= distance and velocity scales for translation into internal units (default from configuration file)
OUTPUT:
(none)HISTORY:
2016-11-02 - Started - Bovy (UofT)
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