Orbital shear parameter
= Orbital shear parameter
{title2=$q=-d\log\Omega/d\log r$}
The orbital shear parameter measures the fractional radial decrease in orbital angular frequency. A <Kepler orbit> has $q=3/2$, while rigid rotation has $q=0$. The <radial epicyclic frequency> obeys $\kappa_r^2=2(2-q)\Omega^2$; this follows by differentiating the squared <specific angular momentum> $h^2=r^4\Omega^2$.