The Fexii195.1 Å/1242 Å emission line ratio in the solar corona

✍ Scribed by F. P. Keenan; S. S. Tayal; R. J. W. Henry

• Publisher: Springer
• Year: 1990
• Tongue: English
• Weight: 262 KB
• Volume: 125
• Category: Article
• ISSN: 0038-0938
• DOI: 10.1007/bf00154779

✦ Synopsis

Recent R-matrix calculations of electron impact excitation rates in FexlI are used to derive the theoretical emission line ratio R I = I(195 1 ~)/I(1242 A,), which as potentially a useful electron density diagnoshc for the solar inner corona (r < 1.05 R o ). These results are found to be significantly different from the earlier estimates of Wlthbroe and Raymond (1984), but are in good agreement with the observed values of R~ for the quiet Sun and an active region. Adoption of the R-matrix atomic data for the 1242 A, line m the coronal iron abundance determination removes an existing discrepancy between results derived from the EUV transxtion and other iron lines m the solar XUV spectrum. The R-matrix calculations confirm the prediction of Wlthbroe and Raymond that the earlier discrepancies in RI and the iron abundance were due to the 1242 ~ line excitation rates being underestimated by a factor of ~ 2. Wlthbroe and Raymond's paper is, therefore, an excellent example of how astronomical observations can be used to accurately predict atomic physics data.