Excitation Rate Coefficients and Line Ratios for the Optical and Ultraviolet Transitions in S II
Abstract
New calculations are reported for electron excitation collision strengths, rate coefficients, transition probabilities, and line ratios for the astrophysically important optical and UV lines in S II. The collision strengths are calculated in the close coupling approximation using the R-matrix method. The present calculations are more extensive than previous ones, including all transitions among the 12 lowest LS terms and the corresponding 28 fine-structure levels in the collisional-radiative model for S II. While the present rate coefficients for electron impact excitation are within 10-30 percent of the previous values for the low-lying optical transitions employed as density diagnostics of H II regions and nebulae, the excitation rates for the UV transitions 4S super 03/2 - 4Psub 1/2,3/2,5/2 differ significantly from earlier calculations, by up to factor of 2. We describe temperature and density sensitive flux ratios for a number of UV lines. The present UV results are likely to be of interest in a more accurate interpretation of S II emission from the Io plasma torus in the magnetosphere of Jupiter, as well as other UV sources observed from the IUE, ASTRO 1, and the HST.
- Publication:
-
The Astrophysical Journal Supplement Series
- Pub Date:
- September 1993
- DOI:
- 10.1086/191824
- Bibcode:
- 1993ApJS...88..329C
- Keywords:
-
- Electron Scattering;
- H Ii Regions;
- Optical Transition;
- Sulfur;
- Transition Probabilities;
- Ultraviolet Spectra;
- Active Galactic Nuclei;
- Collision Parameters;
- Coulomb Collisions;
- Eigenvalues;
- Electron Transitions;
- Io;
- Jupiter (Planet);
- Nebulae;
- Optical Thickness;
- Planetary Magnetospheres;
- Tables (Data);
- Toruses;
- Astrophysics;
- ATOMIC DATA;
- ISM: H II REGIONS;
- GALAXIES: ACTIVE;
- ISM: GENERAL;
- ULTRAVIOLET: GENERAL