Top panels: relation between half-light radii of the Hα emission and those of the stellar continuum radiation in the lowest and highest quartiles of the r-band concentration index for unperturbed galaxies. Bottom panels: the same, but using the half-light radii of the EW_Hα (EW/r parameter). Points are color-coded in quartiles of stellar mass: red for log   (M_∗/M_⊙) ≥ 10.3, orange for 9.8 ≤ log  (M_∗/M_⊙) < 10.3, green for 9.3 ≤ log  (M_∗/M_⊙) < 9.8, and blue for log   (M_∗/M_⊙) < 9.3. The black-contoured big points are the average ratios for each bin of stellar mass.