Alfvén-point compatibility in a plane-parallel sheared flow
= Alfvén-point compatibility in a plane-parallel sheared flow
{c}
At $w^2=v_{az}^2$, the transverse steady equations require $wB_xw'=0$ and $wB_yw'=a(wB_x-B_zv_x)$. These conditions can be lost by division when eliminating transverse magnetic derivatives. A scalar equation displaying the <magnetosonic critical speeds> need not display every compatibility condition at an <Alfvén speed>.