Resonance Scattering of Fe xvii: A Density Diagnostic
Abstract
Resonance scattering of the 15.01 A Fe XVII line, found to be important by Rugge & McKenzie, provides a new density diagnostic for solar active regions that is not subject to the lower density limit of the competing diagnostic. For a 'typical' active region, over 50 percent of the photons for this resonance line could be scattered out of the line of sight. The effect is much stronger for this line than for any other line in the soft X-ray part of the spectrum used routinely to determine active region electron temperatures, emission measures, or densities. Once understood and accounted for in the analysis, the resonance scattering of the 15.01 A Fe XVII line leads to a direct measurement of the density of the active region plasma. In the four active regions studied here, the derived densities range is 1-4 x 10 exp 9/cu cm.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- October 1992
- DOI:
- 10.1086/186590
- Bibcode:
- 1992ApJ...398L.115S
- Keywords:
-
- Line Spectra;
- Metallicity;
- Resonance Scattering;
- Solar Corona;
- Solar X-Rays;
- Iron;
- Solar Maximum Mission;
- X Ray Spectra;
- Solar Physics;
- LINE: FORMATION;
- SUN: CORONA;
- SUN: X-RAYS;
- GAMMA RAYS