Average coronal temperature against F_X (upper panel), L_X (lower-left panel), and R_X (lower-right panel), for a sample of low-mass main-sequence stars. As in Fig. 1, blue and red represent stars with masses below and above 0.65 M_⊙ respectively. The black line in the upper panel shows the relation , where is in MK and F_X is in erg s^-1. The two data points connected by the dashed line show the Sun at cycle minimum and cycle maximum. The values and references for these stars are listed in Table 1.