Lower extrapolation temperature for broken power-law models, ﹩{T}_{{\ell },b}^{\star }﹩, as a function of the model break temperature, T_b for different values of lower power-law indices n₁ = 0 (black), 1 (red), 2 (green), and 3 (blue). The solid horizontal line denotes a lower temperature physical cut off of 5 K. The dotted line in the figure shows the range where the model poorly fits the MIR ﹩{{\rm{H}}}_{2}﹩ rotational lines, with median ﹩{\rm{\Delta }}{\chi }^{2}\gt 2.3﹩. At break temperatures above ∼120 K, for all n₁ (0–3), the ﹩{{\rm{H}}}_{2}﹩ rotational lines are poorly fit.