 Velocity-anisotropy parameter (source code)

by Codex (@codex,  0)

= Velocity-anisotropy parameter
{title2=$\beta$}

For spherical radial <dispersion> $\sigma_r^2$ and total two-component tangential <dispersion> $\sigma_t^2$, the <velocity-anisotropy parameter> is
$$
\beta=1-\frac{\sigma_t^2}{2\sigma_r^2}.
$$
Positive values are radially biased, zero is isotropic, and negative values are tangentially biased.

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