The abundance discrepancy - recombination line versus forbidden line abundances for a northern sample of galactic planetary nebulae

We present deep optical spectra of 23 galactic planetary nebulae, which are analysed in conjunction with archival infrared and ultraviolet spectra. We derive nebular electron temperatures based on standard collisionally excited line (CEL) diagnostics as well as the hydrogen Balmer jump and find that, as expected, the Balmer jump almost always yields a lower temperature than the [O III] nebular-to-auroral line ratio. We also make use of the weak temperature dependence of helium and O II recombination line ratios to further investigate the temperature structure of the sample nebulae. We find that, in almost every case, the derived temperatures follow the relation T e (CEL)