Number density fields in our magneto-hydrodynamical simulation of the supernova remnant of the runaway 20 M_⊙ star rotating with Ω_★/Ω_K = 0.1 and moving with velocity v_★ = 20 km s⁻¹. The evolution of the plerionic supernova remnant is shown at times 2.5 (a), 5.0 (b), 7.5 (c), and 12.5 kyr (d), respectively. The various black contours highlight the region with a 50% contribution of pulsar-wind material. The black arrows in the right parts of the figures are ISM magnetic field lines.