Stars of NGC 2243 and NGC 104 showing M_V, 0 and A(Li) as a function of T_eff. Top: T_eff vs. M_V, 0 of the NGC 2243 (left) and NGC 104 (right). The grey symbols in the left plot show the NGC 2243 stars up to the basis of the RGB (un-evolved stars), while the green symbols show the evolved stars after the basis of the RGB (evolved stars). The pink squares show the five highest Li abundance stars located at the highest T_eff of NGC 2243. The pink diamonds show five stars identified as the ‘basis of the RGB’, and selected with constraints of 5000 < T_eff < 5200 and 1.5 < M_V, 0 < 2.5. The right plot shows NGC 104 stars. The blue symbols are ‘un-evolved’ stars, while the grey symbols are ‘evolved’ stars. The light blue diamonds show 22 stars identified as the ‘basis of the RGB’ for NGC 104, and selected with constraints of 5000 < T_eff < 5200 and 1.8 < M_V, 0 < 2.8. Bottom: T_eff vs. A(Li) of NGC 2243 and NGC 104. Colours and symbols are the same as in the top two graphs. The upside-down triangles show the upper limit of the Li abundance. Temperatures and Li abundances of NGC 104 stars include the −175 K and +0.13 dex corrections (see text).