Log-log plot of the ratio r vs. an estimated stellar mass of the sample in L17 (neglecting the mass of the young stars and assuming the age of the old population in all of the galaxies to be 1.5 Gyr). In the right side, the equivalent scale of the maximum ratio of young stellar mass with respect to the total is given, assuming a minimum factor of 14 in the M _stellar/L ₄₀₀₀ Å between old and young population. The best power-law fit is given by the solid line.