solid, and dashed lines, respectively) for different values of the mid-plane density $n_0$. []{data-label="figN"}](figs/Fig1.eps){width="50.00000%"}

![ Gas temperature (top) and pressure (bottom) along the $z$-axis for values of the mid-plane density $n_0=1.0$, $0.5$, $0.2$, and $0.1$ cm$^{-3}$. []{data-label="figP"}](figs/Fig2.eps){width="50.00000%"}

Given a mid-plane density $n_0$, the vertical structure of the disk is self-consistently computed by the program under the assumptions of ionization, thermal, and hydrostatic equilibrium. An important limitation is that the gas is described by a single density and temperature that may vary with distance, but the coexistence of different phases at the same point is not implemented [see e.g. @BoularesCox90; @SilichTenorio-Tagle98; @Ferriere01; @Cox05 for examples of multiphase models of galaxy disks in hydrostatic equilibrium]. Another simplification is that the radiation field is assumed to strike the system from one side (in our case, the mid plane), whereas in reality the stars are distributed across a scale height comparable to that of the gaseous component [e.g. @MillerCox93; @Robin+03]. With these caveats in mind, it is not surprising that our simple model does not provide a perfect match to the available observational data. It should be able, though, to give a rough estimate of the *volume-averaged* densities and scale heights of the different 