Open AccessExtreme ultraviolet transitions of Fe xxi in solar, stellar and laboratory spectra
Author(s) -
Keenan F.P.,
Aggarwal K.M.,
Williams D.R.,
Mathioudakis M.,
Phillips K.J.H.
Publication year - 2001
Publication title -
monthly notices of the royal astronomical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.058
H-Index - 383
eISSN - 1365-2966
pISSN - 0035-8711
DOI - 10.1111/j.1365-2966.2001.04686.x
Subject(s) - physics , spectral line , solar flare , line (geometry) , atomic physics , extreme ultraviolet , plasma , electron density , astrophysics , electron , tokamak , electron temperature , solar physics , ultraviolet , astronomy , nuclear physics , optics , laser , geometry , mathematics
Recent R ‐matrix calculations of electron impact excitation rates for transitions among the 2s 2 2p 2 , 2s2p 3 and 2p 4 levels of Fe xxi are used to derive theoretical electron density ( N e ) sensitive emission‐line ratios involving 2s 2 2p 2 –2s2p 3 transitions in the ∼98–146Å wavelength range. A comparison of these with observations from the PLT tokamak plasma, for which the electron density has been independently determined, reveals generally very good agreement between theory and experiment, and in some instances removes discrepancies found previously. The observed Fe xxi ratios for a solar flare, obtained with the OSO–5 satellite, imply electron densities which are consistent, with discrepancies that do not exceed 0.2 dex. In addition, the derived values of N e are similar to those estimated for the high‐temperature regions of other solar flares. The good agreement between theory and observation, in particular for the tokamak spectra, provides experimental support for the accuracy of the present line‐ratio calculations, and hence for the atomic data on which they are based.