PACS 70 μm image of R Leo (left Cox et al. 2012) compared to a hydrodynamical simulation of the wind-ISM interaction computed with the AMRVAC code (van Marle et al. 2011). The parameters for this simulation are a stellar wind velocity of 15 km s^-1, a constant gas mass-loss rate of 1 × 10^-6   M_⊙/yr, a dust-to-gas mass ratio of 0.01, a space velocity of 25 km s^-1, a local ISM density of 2 cm^-3, and an ISM temperature of 10 K. The upper right figure shows the gas density, which ranges (on log scale) between 10^-24 and 10^-19 g/cm³; the lower right figure represents the dust grain particle density, ranging (on log scale) between 10^-10 and 10^-3.5 cm^-3.