The High-Excitation Planetary Nebula NGC 7662
Wavelengths and identifications have been provided for approximately 300 lines between 3660 and 10125 Å in the spectrum of the archetypal bright, high-excitation planetary nebula NGC 7662. These lines are measured with the Hamilton echelle spectrograph at Lick Observatory and are supplemented by image-tube data. Published results are used to construct diagnostic diagrams and derive ionic concentrations. The electron temperature indicated by [O III] is about 12,500 K; the density regimes consist of Nɛ = 5000-17,000 cm-1. Derivation of precise abundances will require appropriate model calculations, but with the aid of homogeneous spherical model procedures we find C to be enhanced, N marginally so if at all, and heavier elements depleted with respect to the Sun. These conclusions are in harmony with those of Barker.
The Astrophysical Journal
- Pub Date:
- December 1997
- ISM: Abundances;
- Line: Identification;
- ISM: Planetary Nebulae: Individual: NGC Number: NGC 7662