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Published online by Cambridge University Press: 22 September 2016
A method of determination of the electron temperature in the He++ regions in planetary nebulae from observed intensities of [NeV] λ3426 and [NeIV] λ4714–25 relative to HeII λ4686 is presented. It has been used for 22 planetary nebulae for which the observational data have been taken from Kaler's Catalogue (Ap. J. Suppl., 31, 517). The electron temperatures in the He++ regions range from 15,000°K to 30,000°K for most of the studied planetaries and are usually significantly higher than the temperatures determined from [01II] lines which refer to the He++ regions. A correlation between the electron temperatures and effective temperatures of central stars has been found; the planetaries with hotter nuclei have slightly higher electron temperatures in the He++ regions. Finally, intensities of ultraviolet lines of [NeV] λ2975 and [NeIV] λ2424 have been predicted for the studied nebulae.