Central stars of planetary nebulae and the evolution of post-AGB stars

An overview of PN central-star evolution is given, summarizing the results of recent observational and theoretical investigations. Consideration is given to the variation of envelope mass with efficient temperature for post-AGB stars evolving to the blue region of the HR diagram, evolutionary tracks for different hydrogen-burning models, and discrepancies between theoretical predictions and observations. It is shown that PN formation is initiated in the quiescent hydrogen-burning phase rather than at a luminosity peak; however, the existence of He-burning central stars is not ruled out. 26 references