Magnetospheric truncation radius
= Magnetospheric truncation radius
{title2=$r_m$}
The inner radius at which a stellar <magnetic dipole field> disrupts a surrounding <accretion disk>. In a <free fall> <pressure>-balance estimate with fixed aspect ratio $\epsilon=H/r$, $r_m\sim(\epsilon^2\mu^4/(GM\dot M^2))^{1/7}$. Geometry and inflow structure change its numerical coefficient.