Volume 574, February 2015
|Number of page(s)||11|
|Section||Atomic, molecular, and nuclear data|
|Published online||30 January 2015|
Benchmarking atomic data for astrophysics: Si iii⋆
DAMTP, Centre for Mathematical Sciences, Wilberforce Road,
2 Department of Physics, University of Strathclyde, Glasgow, G4 0NG, UK
Received: 13 June 2014
Accepted: 20 November 2014
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.
Key words: atomic data / techniques: spectroscopic / Sun: corona / line: identification
The full dataset (energies, transition probabilities and rates) are available in electronic form at our APAP website (www.apap-network.org)
© ESO, 2015
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