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 Rmatrix method. The present calculations are more extensive than previous ones, including all transitions among the 12 lowest LS terms and the corresponding 28 finestructure levels in the collisionalradiative model for S II. While the present rate coefficients for electron impact excitation are within 1030 percent of the previous values for the lowlying optical transitions employed as density diagnostics of H II regions and nebulae, the excitation rates for the UV transitions 4S super 0_{3/2}  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