A study of small diffuse nebulae
Abstract
Ten small galactic H II regions have been studied by filter photometry at the Prairie Observatory of the University of Illinois and with the Harvard Scanner at Kitt Peak National Observatory. Absolute H-alpha and H-beta fluxes were determined for all 10, and fluxes in the O II 3727, O II 7324, O III 5007 + 4959, and N II 6584 + 6548 forbidden lines were also obtained. Extinction constants were calculated from H-alpha/H-beta ratios and also from the radio/H-beta ratios when possible. Differences between the optical extinctions and the radio extinctions are found for six of the eight regions with known radio fluxes; the observed differences can be explained by local dust. Electron temperatures from forbidden O II are found to lie within the range 5000-7500 K, but these temperatures should be regarded as lower limits to the actual forbidden O II electron temperatures.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- April 1981
- DOI:
- 10.1086/158830
- Bibcode:
- 1981ApJ...245..560M
- Keywords:
-
- Abundance;
- Interstellar Extinction;
- Line Spectra;
- Nebulae;
- Spectrum Analysis;
- Astronomical Photometry;
- Electron Density (Concentration);
- Electron Energy;
- H Ii Regions;
- H Lines;
- Nitrogen;
- Oxygen Spectra;
- Astronomy