Column a: bottom: proper size distribution (R_eff) for Fe ii* emitters based on the HST Y-band semi-major axis measurements. The grey histogram shows the proper size distribution for 69 [O ii] emitters with SFR ≥ + 0.5 M_⊙ yr^-1. The red histogram shows the subpopulation of Fe ii* emitters with confidence flag qc> 1 (23 galaxies). White hatching indicates Fe ii* emitters within this SFR range that also have Mg ii emission or P Cygni profiles (8 galaxies). Top: the fraction of Fe ii* emitters. Error bars represent the 68% confidence interval as in Fig. 1. Column b: bottom: proper size distribution (R_eff) for Mg ii emitters based on the HST Y-band semi-major axis measurements. The grey histogram shows the proper size distribution for 133 [O ii] emitters with −0.5 M_⊙ yr^-1≤ SFR ≤ + 0.5 M_⊙ yr^-1. The blue histogram shows the subpopulation of Mg ii emitters with confidence flag qc> 1 (17 galaxies). White hatching indicates Mg ii emitters within this SFR range that also have Fe ii* emission (1 galaxy). Top: the fraction of MgII emitters.