Ca II H and K analysis of the WiFeS spectrum for HD 54236B against stars with similar T_eff from three different open clusters spanning the range of ages estimated from the Li abundances in Section 4.5.1. Against the Ca II H and K analysis for HD 54236B (black line). Top: comparison with IC 2391 (age ∼50 Myr). Middle: comparison with Pleiades (age ∼130 Myr with a range of T_eff from 4200 K to 5420 K). Bottom: comparison with M7 (age ∼300 Myr). The open cluster spectra were taken from Keck HIRES and VLT UVES public archives and convolved to match the resolution of the WiFeS observation of HD 54236B. Taken together, these comparisons strongly imply an age of HD 54236B older than the Pleiades (∼130 Myr) and clearly younger than M7 (∼300 Myr).