The optical and ultraviolet spectrum of the planetary nebula NGC 2440.
Abstract
New measurements of the optical and ultraviolet emission-line intensities of the high-excitation planetary nebula NGC 2440 in the wavelength range 1240-8578 A are analyzed with the aid of photoionization models. The observed O III and N II forbidden-line temperatures (13,800 K and 10,000 K, respectively) differ by more than the models predict. Inclusion of charge-transfer reactions at published rates improves agreement between calculated and observed abundances of many ions, but worsens the agreement for several highly ionized ions. Nitrogen shows a larger overabundance N(N)/N(O) approximately equal to 1.0, whereas ultraviolet lines give a carbon abundance close to the solar value. The refractory elements magnesium, calcium, and iron have similar gas-phase depletions of approximately 1.5 dex. The abundances of oxygen, neon, sodium, sulfur, chlorine, potassium, and argon are rougly solar.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- September 1981
- DOI:
- 10.1086/159182
- Bibcode:
- 1981ApJ...248..569S
- Keywords:
-
- Astronomical Spectroscopy;
- Optical Emission Spectroscopy;
- Planetary Nebulae;
- Ultraviolet Astronomy;
- Visible Spectrum;
- Abundance;
- Astronomical Models;
- Charge Transfer;
- Emission Spectra;
- Nitrogen;
- Oxygen;
- Photoionization;
- Astrophysics