Evolution of stars in the H‐R diagram for varying treatments of opacity. All stars have mass M_* = 0.25 M_☉. The collection of evolutionary tracks corresponds to different opacity laws with increasing sensitivity at high temperatures, i.e., different values of T_W (as labeled). As the opacity law becomes a more steeply rising function of temperature (as T_W decreases), the stars more readily attain red giant‐like configurations in general accordance with the theoretical arguments of § 4.