Accession Number : AD0787204

Title :   Relative Coronal Abundances Derived from X-ray Observations III: The Effect of Cascades on the Relative Intensity of Fe XVII Line Fluxes, and a Revised Iron Abundance,


Personal Author(s) : Walker,Arthur B. , Jr. ; Rugge,Hugo R. ; Weiss,Kay

Report Date : 01 OCT 1974

Pagination or Media Count : 43

Abstract : Lines of Fe XVII are prominent in the coronal spectrum below 25 A. The intensities of the lines of the 2p-3d transitions near 15 A have been used in conjunction with coronal models, and the assumption that the excited states are populated only by collisional excitation from the ground state ('coronal excitation'), to determine the Fe abundance. Eight lines of Fe XVII were observed which originated from the (2p)5(3s), (2p)5(3d) and (2s)(2p)6(3d) configurations in the coronal spectrum between 13 and 18 A. Using a more complete theoretical model, and higher resolution observations which allow a number of line blends to be resolved, the authors have revised earlier calculation of the coronal abundance of Fe, and find an iron abundance relative to hydrogen of .000026, which is in excellent agreement with the photospheric iron abundance. (Modified author abstract)

Descriptors :   *Solar corona, *Iron, *Solar spectrum, Stripped atoms, Atomic energy levels, Photosphere, Spectral lines, Electronic states, Soft x rays, Excitation, Rates, Electron transitions

Subject Categories : Astrophysics
      Atomic and Molecular Physics and Spectroscopy

Distribution Statement : APPROVED FOR PUBLIC RELEASE