Normalized indices of Hα emission, ﹩R_{\mathrm{H}\,\alpha }﹩, vs. ﹩N^{\prime }_{\mathrm{R}\,}﹩, the normalized ﹩v\mathrm{sin}\,i﹩ equivalent to a Rossby number. For the Pleiades, upper limits to ﹩v\mathrm{sin}\,i﹩ are not shown, and for both the Pleiades and M34 stars with overt Hα emission are highlighted. In the bottom panel, the solid points are for M34 and the crosses are for the Pleiades.