2D view of the second hydrostatic core formed as a result of the collapse of a 5 M_⊙ (top), 10 M_⊙ (middle), and 20 M_⊙ (bottom) cloud core with an initial temperature of 10 K. The four panels in each of the subplots show the (a) Mach number, (b) density, (c) temperature, and (d) entropy within the inner 0.5 au of an initial 3000 au cloud core. The velocity streamlines in black indicate the material falling onto the second core and the mixing inside the core. The white contour in panel a showing Mach = 1.0 separates the sub- and supersonic regions. The different contour lines in panel b show the increase in density towards the centre. The plots are shown at 128 years, 91.4 years, and 86.4 years after the second core formation, for the 5 M_⊙, 10 M_⊙, and 20 M_⊙ cases, respectively.