[N-II] AND [O-III] MEAN ELECTRON TEMPERATURES IN PLANETARY-NEBULAE

Mean electron temperatures for 106 planetary nebulae are presented, wh ich have been derived using calculations of the values of electron tem perature-sensitive line ratios involving-forbidden transitions among t he 2s(2) 2p(2) P-3, D-1, and S-1 levels of N+ and O++, based on new el ectron impact rates and transition probabilities. Comparison of these results with values of T-e [N II] and T-e [O III] determined previousl y by Kaler reveals that the present electron temperatures are systemat ically lower for both ions, and that this discrepancy is correlated wi th the electron density in the nebula. It is also shown that the avera ge difference between T-e [N II] and T-e [O III] in a planetary nebula is somewhat smaller than that derived by Kaler, with the present resu lts implying that the N II and O III temperatures disagree on average by 2070 K as opposed to the 2210 K average-found by Kaler.