Log of n_H (greyscale) and gas velocity relative to the star (coloured arrows) for simulation V04, with units log  (n_H/ cm^-3) and km s^-1, respectively. The radial direction is vertical, and the axis of symmetry is R = 0, the z-axis. The solid black contour shows x = 0.5. The star is at the origin, denoted by a white cross. Regions with gas velocity >30 km s^-1 are excluded from the velocity plot for clarity, and velocities from 20 to 30 km s^-1 all have the same colour arrows (yellow). An animation of the simulation’s evolution is available online.