The relationship between T_eff and EW_Hα (left panels) and between T_eff and the residual ﹩{{\rm{EW}}}_{{\rm{H}}\alpha }^{{\rm{{\prime} }}}﹩ (right panels). In the left panels, points are colored by ﹩\mathrm{log}g﹩, and the red line represents a third-degree polynomial fit to the least active 2% of stars in each 100 K temperature bin. In the right panels, the color indicates the number density of stars, the black dashed line marks ﹩{{\rm{EW}}}_{{\rm{H}}\alpha }^{{\rm{{\prime} }}}=0﹩, and the black dotted line connects median residuals in 500 K temperature bins. The upper row corresponds to low-resolution data, and the lower row corresponds to medium-resolution data.