Stellar luminosity as a function of the lithium abundance in stars for different models. Panel (a): stellar luminosity as a function of the lithium abundance in stars with different stellar mass without IGWs. Panel (b): stellar luminosity as a function of the lithium abundance in stars with different stellar mass with IGWs. Panel (c): stellar luminosity as a function of the lithium abundance in stars with a 1.3 M_⊙ model in different initial rotational velocities without IGWs. Panel (d): stellar luminosity as a function of the lithium abundance in stars with different initial rotational velocities with IGWs. The yellow circles are RC stars and the green ones are red giant stars. They are from Kumar et al. (2020).