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The Coronal X-Spectrum: Problems and Prospects*

Published online by Cambridge University Press:  12 April 2016

A.B.C. Walker Jr.
A.B.C. Walker Jr.*
Affiliation:
Space Physics Laboratory, The Aerospace Corporation, El Segundo, Calif. 90245, U.S.A.

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The coronal spectrum provides a unique opportunity to probe atomic processes in a high temperature plasma. The corona is optically thin, at low density, and the coronal ions are highly stripped. These characteristics result in an emission line spectrum with a rich multiplet structure, with forbidden lines prominent in the spectrum, and deexcitation of metastable states by two photon decay making significant contributions to the continuum. The multiplet structure is further complicated by the presence of satellite lines from autoionizing states formed during recombination. With few exceptions, the true coronal lines are below 300 Å, and the general necessity for and complexity of grazing incidence optics has made it difficult to obtain high resolution spectroheliograms.

Type
Section IV / The Solar Soft X-Ray Spectrum
Information
International Astronomical Union Colloquium , Volume 14: Special Issue: Ultraviolet and X-Ray Spectroscopy of Astrophysical and Laboratory Plasmas , November 1972 , pp. 672 - 730
Copyright
Copyright © Reidel 1972

Footnotes

*

This work was conducted under U.S. Air Force Space and Missile Systems Organizatisn (SAMSO) Contract No. F 04701-70-0059.

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