Volume fraction of gas in the ρ − T plane for simulation 3D-3-by7 at times t = 0.35 Myr (top), 0.39 Myr (middle) and 0.43 Myr (bottom). The colour scale shows log₁₀ of the fraction of the simulation volume within the density and temperature range enclosed by each pixel. These simulations have the ISM magnetic field in configuration 2, almost perpendicular to the space velocity of the star through the ISM. The black line shows a line of constant pressure, p/k_B ≈ 10⁴ cm⁻³ K.