Volume 543, July 2012
|Number of page(s)||10|
|Section||Atomic, molecular, and nuclear data|
|Published online||12 July 2012|
Atomic data for astrophysics: Fe xii soft X-ray lines⋆
1 DAMTP, Centre for Mathematical Sciences, Wilberforce Road, Cambridge, CB3 0WA, UK
2 Department of Physics and Astronomy, University College London, Gower Street, London, WC1E 6BT, UK
3 Department of Physics, University of Strathclyde, Glasgow, G4 0NG, UK
Received: 12 February 2012
Accepted: 30 May 2012
We present new large-scale R-matrix (up to n = 4) and distorted-wave (DW, up to n = 6) scattering calculations for electron collisional excitation of Fe xii. The first aim is to provide accurate atomic data for the soft X-rays, where strong decays from the n = 4 levels are present. As found in previous work on Fe x, resonances attached to n = 4 levels increase the cross-sections for excitations from the ground state to some n = 4 levels, when compared to DW calculations. Cascading from higher levels is also important. We provide a number of models and line intensities, and list a number of strong unidentified lines. The second aim is to assess the effects of the large R-matrix calculation on the n = 3 transitions. Compared to our previous (n = 3) R-matrix calculation, we find overall excellent agreement to within a few percent, however a few key density diagnostic EUV intensities differ by about 60% at coronal densities. The new atomic data result in lower electron densities, resolving previous discrepancies with solar observations.
Key words: atomic data / line: identification / techniques: spectroscopic / Sun: corona
The full dataset (energies, transition probabilities and rates) are available in electronic form at our APAP website (http://www.apap-network.org) as well as at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (18.104.22.168) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/543/A139
© ESO, 2012
Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.
Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.
Initial download of the metrics may take a while.