A&A 436, 953-965 (2005)
1 Kapteyn Astronomical Institute, PO Box 800, 9700 AV Groningen, The Netherlands
2 SRON Laboratory for Space Research, PO Box 800, 9700 AV Groningen, The Netherlands
3 Laboratory for Astronomy and Solar Physics, Code 681, Goddard Space Flight Center MD, USA
(Received 30 December 2004 / Accepted 11 March 2005)
The ISO and IUE spectra of the elliptical nebulae are presented. These spectra are combined with the spectra in the visual wavelength region to obtain a complete, extinction corrected, spectrum. The chemical composition of the nebulae is then calculated and compared to previous determinations. A discussion is also given of the exciting stars of the nebulae, and possible evolutionary effects.
Key words: ISM: abundances -- ISM: planetary nebulae: individual: NGC 2022 -- ISM: planetary nebulae: individual: NGC 6818 -- ISM: planetary nebulae: individual: IC 4191
© ESO 2005