Migration map for discs with an α transition. The discs feature Ṁ = 5 × 10^-8 M_⊙/yr (top) and Ṁ = 1 × 10^-8 M_⊙/yr (bottom). The regions encircled in black mark regions in which outward migration is possible. The vertical red line in the top plot marks the ice line at 190 K. The bottom plot has a different colour scale.