Coronal activity R_x vs. chromospheric activity $R_{\mathrm{HK}}^{\prime }$. Our sample have 26 stars with R_x, three of them are from Wang et al. (2020) and the rest are from Pizzocaro et al. (2019). The green dashed line is given by Mamajek & Hillenbrand (2008), for which the boundary of the gray area indicates 1-σ level of the residuals of all the points. The symbol of five-pointed star indicates common stars among $R_{\mathrm{HK}}^{\prime }$, R_X and R_flare. The size of symbols represents the surface gravity log g which is the same as Fig. 6