Fragmentation rate ϕ as a function of spatial scale R for isothermal EOS and different values of mass transfer rate ξ with cloud initial size R₀ = 10 pc and initial density ρ₀ = 10⁻²¹ g/cm³. The hatched area represents the ϕ ⩽ 0 space in which there is no hierarchical fragmentation. The grey vertical line separates turbulent (supersonic) fragmentation from thermal (subsonic) fragmentation.