SIMBAD references

Two-dimensional hydrodynamical simulations are presented from the formation up to the late evolution of planetary nebula, for six different stellar models from 1 to 5 M$_{\odot }$. The hydrodynamical models use stellar evolution calculations as inner boundary conditions and updated values for the number of ionizing photons. Special emphasis is placed on the formation of neutral spikes, as recently observed by the James Webb Space Telescope. The results indicate that neutral spikes can be detected either at the formation of planetary nebulae or in their decline. In the first case, the temporal window decreases with the mass of the model, ranging from 3000 yr in the 1 M$_{\odot }$ case to 0 for 5 M$_{\odot }$. In the second case, only the 1.5, 2.0, and 2.5 M$_{\odot }$ cases allow us to detect the neutral spikes for most of the remaining time.