White-dwarf envelope thickness-luminosity relation
= White-dwarf envelope thickness-luminosity relation
{title2=$s_1/s_2=(L_1/L_2)^{2/7}$}
For fixed mass, degenerate radius and composition, the <matching of a white-dwarf envelope to a degenerate core> gives $L\propto T_c^{7/2}$, while the <geometrical thickness of a white-dwarf radiative envelope> gives $s\propto T_c$ to leading thin-layer order. Cooling therefore thins this idealized envelope. At finite thickness the ratio additionally contains $(1+q_2)/(1+q_1)$.