Calculations of the Zn ii UV mult. 1 2062.660 Å absorption line based on a hydrodynamic simulation including ionization with Ṁ = 10^-6 M_⊙ yr^-1 and ν_∞ = 20 km s^-1, and on an undisturbed, spherically expanding wind. As a convergence test, the hydrodynamic results (low resolution) are compared to a model with the same parameters but with a resolution that is increased by a factor of two (high resolution). The difference in the component at ~−29 km s^-1 is due to the reduced size of the computational domain in the high-resolution simulation (see text). The abscissa gives the radial velocity relative to the center of mass of the system.