SIMBAD references

We have constructed a distance-independent diagram to test published theoretical tracks for the evolution of post-AGB stars by comparing them with the Galactic planetary nebulae data base. We have found no inconsistency between observations and the set of tracks computed by Schoenberner (1981, 1983) and Bloecker & Schoenberner (1990). On the other hand, observations do not seem support the large transition times between the end of the AGB superwind and the beginning of the planetary nebula ionization phase adopted in the models of Vassiliadis & Wood (1994).