Population ratios for the fine structure ground state of SI II applicable to the interstellar medium
Abstract
Using recent R-matrix calculations of electron excitation rates for the 3s23p2P1/2-3s23p2P3/2 fine structure transition in Si II, the electron density sensitive population ratio n(2P3/2)/n(2P1/2) has been derived for the ranges of temperature (100 - 20000K) and hydrogen density (0 - 1000 cm-3) applicable to H I and H II regions. The results differ appreciably from those of Smeding & Pottasch, and lead to electron density estimates approximately 30 to 40 per cent larger.
- Publication:
-
Monthly Notices of the Royal Astronomical Society
- Pub Date:
- June 1985
- DOI:
- 10.1093/mnras/214.1.37P
- Bibcode:
- 1985MNRAS.214P..37K
- Keywords:
-
- Elementary Excitations;
- Fine Structure;
- Ground State;
- Interstellar Matter;
- Silicon;
- Electron Density (Concentration);
- H Ii Regions;
- Nebulae;
- Astrophysics