Column a: bottom: axis ratio (b/a) distribution for the Fe ii* emitters from the HST Y-band. The grey histogram shows the distribution for 69 [O ii] emitters with SFR ≥ + 0.5 M_⊙ yr^-1, and 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 for the nine axis ratio bins. Error bars represent the 68% confidence interval as in Fig 1. Column b: bottom: axis ratio (b/a) distribution for the Mg ii emitters from the HST Y-band. The grey histogram shows the distribution for 133 [O ii] emitters with −0.5 M_⊙ yr^-1≤ SFR ≤ + 0.5 M_⊙ yr^-1, and 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 Mg ii emitters for the nine axis ratio bins.