Atomic Data and Spectral Line Intensities for Si VII
Abstract
Electron impact collision strengths, energy levels, oscillator strengths, and spontaneous radiative decay rates are calculated for the Si VII configurations 2s^{2}2p^{4}, 2s2p^{5}, 2p^{6}, 2s^{2}2p^{3}3s, 2s^{2}2p^{3}3p, and 2s^{2}2p^{3}3d, giving rise to 86 finestructure levels in intermediate coupling. Collision strengths are calculated at five incident energies, 15, 30, 45, 60, and 75 ryd, using the distorted wave approximation. Excitation rate coefficients are calculated as a function of electron temperature by assuming a Maxwellian electron velocity distribution. Using the excitation rate coefficients and the radiative transition rates, statistical equilibrium equations for level populations are solved at electron densities covering the range of 10^{8}10^{14} cm^{3} assuming an electron temperature of logT_{e}(K)=5.8, corresponding to maximum ionic abundance of Si VII. Relative spectral line intensities are calculated. Proton excitation rates between the lowest three levels have been included in the statistical equilibrium equations. The predicted Si VII line intensities are compared with Solar EUV Rocket Telescope and Spectrograph (SERTS) observations in NOAA Active Region 5464 and Solar Ultraviolet Measurement of Emitted Radiation (SUMER) observations of the quiet Sun.
 Publication:

The Astrophysical Journal
 Pub Date:
 March 2003
 DOI:
 10.1086/345930
 Bibcode:
 2003ApJ...585..587B
 Keywords:

 Atomic Data;
 Plasmas