a) First core radius as a function of time, where t = 0 corresponds to the time when the first core accretion shock is formed. The different colours represent different initial cloud temperatures T₀ (see legend). The thick black line is for run 69. b) First core radius as a function of central density (solid lines), alongside the (re-scaled) analytical predictions of Masunaga et al. (1998, dashed lines). The colour coding is the same as in panel a). c) Difference between the downstream gas pressure and the upstream ram pressure. d) Downstream gas pressure (blue), upstream ram pressure (red) and radiation pressures (greens) just upstream (subscript 1) and downstream (subscript 2) of the first core accretion shock, in run 69. The upstream radiative fluxes, scaled with the local gas velocity for dimensional coherence, are also plotted for relative comparison in the total energy budget (black). e) First core accretion shock compression ratio for run 69 measured in the simulation (black) and predicted for a non-radiative shock (red).