Electron impact excitation of Be-like ions: a comparison of DARC and ICFT results
Abstract
Emission lines of Be-like ions are frequently observed in astrophysical plasmas, and many are useful for density and temperature diagnostics. However, accurate atomic data for energy levels, radiative rates (A-values) and effective electron excitation collision strengths (Υ) are required for reliable plasma modelling. In general, it is reasonably straightforward to calculate energy levels and A-values to a high level of accuracy. By contrast, considerable effort is required to calculate Υ, and hence it is not always possible to assess the accuracy of available data. Recently, two independent calculations (adopting the R-matrix method) but with different approaches (DARC and ICFT) have appeared for a range of Be-like ions. Therefore, in this work we compare the two sets of Υ, highlight the large discrepancies for a significant number of transitions and suggest possible reasons for these.
- Publication:
-
Monthly Notices of the Royal Astronomical Society
- Pub Date:
- March 2015
- DOI:
- 10.1093/mnras/stu2727
- arXiv:
- arXiv:1501.00808
- Bibcode:
- 2015MNRAS.447.3849A
- Keywords:
-
- atomic data;
- atomic processes;
- Astrophysics - Solar and Stellar Astrophysics;
- Physics - Atomic Physics
- E-Print:
- 9 pages including 2 figures, will appear in 2015 MNRAS