= Accretion Alfvén radius
{title2=$r_{\rm Alf}$}
The <accretion Alfvén radius> estimates where the magnetic <stress> of an accreting <star> competes with inflow <stress> and disrupts an approximately <Keplerian disk>. It is distinct from the Alfvén critical <radius> of an outgoing stellar wind. A dipole and a free-fall <pressure> estimate give the characteristic $B_*^{4/7}\dot M^{-2/7}$ scaling; the numerical coefficient depends on flow geometry, and an inferred <radius> inside the <star> is outside the model's domain.
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