(a) Same as Figure 1 for χ² Hya. Primary values of ﹩{f}_{\mathrm{ov}}=0.010﹩ are in the rapid phase of evolution and are regarded as less likely. (b) ﹩{\alpha }_{\mathrm{MLT}}﹩ for both stars restricted to the CB2018 value of ﹩{{\alpha }_{\mathrm{MLT}}}_{\odot }=1.60﹩ (dots), or to a value of 1.80 near our solar-calibrated mixing length (squares). The corresponding viable areas of parameter space are indicated by the hatched regions. (c) Same as panel (a), adding the constraint from the measured temperature ratio (see text). (d) Same as panel (b), adding the constraint from the measured temperature ratio.