High dispersion EUV observations of planetary nebulae.

Abstract

The three high-excitation planetary nebulae NGC 3242, NGC 7009, and NGC 6210 have been observed by the IUE satellite in the 1190-1930 A wavelength range using the high resolution mode. The most prominent emission lines are the He II 1640 A and C III 1909 A lines. The C IV 1550 A lines of NGC 3242 and NGC 7009 are in emission but weaker than in NGC 7027, whereas in NGC 6210 they show up as absorption lines. This may suggest that the central star of NGC 6210 is an O subdwarf. In all three objects the 2P(0)1/2-2D3/2 line of the C II resonance transition is in absorption and the 2P(0)3/2-2D5/2 line is in emission.