Bibcode
                                    
                            DOI
                                    
                            McCarthy, J. K.; Mould, J. R.; Mendez, R. H.; Kudritzki, R. P.; Husfeld, D.; Herrero, A.; Groth, H. G.
    Bibliographical reference
                                    Astrophysical Journal, Part 1 (ISSN 0004-637X), vol. 351, March 1, 1990, p. 230-244. Research supported by the Max-Planck-Institut für Physik und Astrophysik.
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                        3
            
                        1990
            
  Journal
                                    
                            Citations
                                    52
                            Refereed citations
                                    43
                            Description
                                    The disagreement between evolutionary and dynamical time scales for the
evolution of the central stars of planetary nebulae (CSPN) through the
H-R diagram is investigated. Three possible reasons for the disagreement
are examined: (1) the nebulae could have experienced a phase of rapid
photoionization of material ejected previously while the stars were
still on the AGB; (2) the central stars could have undergone a late
helium shell flash and returned to the AGB; and (3) the AGB-CSPN
evolutionary transition times could have been increased by small
additional amounts of residual envelope material remaining after the
superwind mass-loss phase. Mechanism (3) is favored here because it can
account for evolutionary ages both less than and greater than the
corresponding dynamical ages.