Opened 3 years ago

#318 new enhancement

Si III data update

Reported by: Gary J. Ferland Owned by: nobody
Priority: good to do Milestone:
Component: atomic/molecular data base Version: trunk
Keywords: Cc:


Benchmarking atomic data for astrophysics: Si iii
Del Zanna, G.; Fernández-Menchero, L.; Badnell, N. R.
AA(DAMTP, Centre for Mathematical Sciences, Wilberforce Road, Cambridge, CB3 0WA, UK, AB(Department of Physics, University of Strathclyde, Glasgow, G4 0NG, UK), AC(Department of Physics, University of Strathclyde, Glasgow, G4 0NG, UK)
Astronomy & Astrophysics, Volume 574, id.A99, 11 pp. (A&A Homepage)
Publication Date:	
EDP Sciences
Astronomy Keywords:	
atomic data, techniques: spectroscopic, Sun: corona, line: identification
Bibliographic Code:	

We investigate the main spectral diagnostics for Si iii UV lines, which have been previously used to measure electron densities, temperatures, and to suggest that non-Maxwellian electron distributions might be present in the low transition region of the solar atmosphere. Previous atomic calculations and observations are reviewed. We benchmark the observations using a new large-scale R-matrix scattering calculation for electron collisional excitation of Si iii, carried out with the intermediate-coupling frame transformation (ICFT) method. We find generally good agreement between predicted and observed line intensities, if one takes into account the different temperature sensitivity of the lines, and the structure of the solar transition region. We find no conclusive evidence for the presence of non-Maxwellian electron distributions.
The full dataset (energies, transition probabilities and rates) are available in electronic form at our APAP website (

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