Spectrophotometry of planetary nebulae. I. Physical conditions.
Abstract
Emission-line intensities have been measured photoelectrically for 35 planetary nebulae in the spectral region 3400-7400 A. Reddening-corrected observations of the lower Balmer decrement agree well with theoretical calculations. There is also generally good agreement between the electron temperatures and densities determined from different forbidden-line intensity ratios, although there are some cases of systematic disagreement, especially in the case of forbidden O II. Electron temperatures based on the strength of the Balmer continuum are consistent with those found from forbidden lines. Bowen fluorescent efficiencies calculated from the 3444-A/4686-A intensity ratio are generally close to the predicted value of 0.5, but two nebulae with low efficiencies should be investigated theoretically. Two or three of the nebulae (VV 8, M 3-27, and possibly Hb 12) are undergoing Balmer-line self-absorption and have a wide range of electron temperatures and densities within them.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- February 1978
- DOI:
- 10.1086/155854
- Bibcode:
- 1978ApJ...219..914B
- Keywords:
-
- Balmer Series;
- Electron Energy;
- Planetary Nebulae;
- Spectrophotometry;
- Electron Density (Concentration);
- Energy Absorption;
- Forbidden Bands;
- Oxygen Ions;
- Self Absorption;
- Astronomy;
- Planetary Nebulae:Spectrophotometry