Forbidden lines from inhomogeneous nebulae: the case of a density distribution N ∝ r^{2}.
Abstract
The formation of forbidden lines in a nebula with density inversely proportional to the square of r is considered. We show that the forbiddenlineintensity ratios (FLIR) may mimic those of constant density nebulae, whose physical conditions differ considerably from the actual ones. The limits of a FLIR analysis in terms of a constant density model are discussed. We find that a selfconsistent analysis is necessary for a correct interpretation of FLIR data, otherwise quite misleading results may be obtained: i.e., overestimate of the minimum density and the electron temperature, underestimate of the maximum density and the abundances relative to hydrogen, ad hoc ionization structure.
 Publication:

Astronomy and Astrophysics
 Pub Date:
 September 1975
 Bibcode:
 1975A&A....43...93P
 Keywords:

 Density Distribution;
 Electron Density (Concentration);
 Electron Energy;
 Forbidden Bands;
 Nebulae;
 Abundance;
 Astronomical Models;
 Gas Ionization;
 Hydrogen;
 Temperature Distribution;
 Astrophysics