K-corona

K-corona

The inner part of the solar corona, responsible for the greater part of its intensity out to a distance of about two solar radii. It consists of rapidly moving free electrons, and exhibits a linearly polarized continuous spectrum owing to Thomson scattering, by the electrons, of light from the photosphere. The Fraunhofer lines are not present in the spectrum: they have been sufficiently broadened by the large Doppler shifts resulting from the rapid random motion of the electrons as to overlap and be indiscernible. The K-corona attains a temperature of around 2 000 000 kelvin at a height of about 75 000 km. It may exhibit considerable structure, with streamers (regions of higher than average density) overlying active regions and quiescent prominences, and coronal holes (regions of exceptionally low density) overlying areas characterized by relatively weak divergent (and therefore primarily unipolar) magnetic fields.
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As a consequence of such early studies, it was established that the light arising from the K-corona was radially polarized [18].
In this regard, the LMHSM provides a strong platform to account for the polarization of the K-corona, enabling polarized self-emission from an anisotropic structure.
It is easy extend this example to the k-corona model.
We regard the ECT scheme with k-corona model as ECT-k.
Measuring the polarization enables us to separate the "Fraunhofer corona" of dust, which shows the spectrum of the solar photosphere, from the normal electron "K-corona" visible during eclipses.
The white light emitted by the K-corona is readily visualized during solar eclipses.
As for the Fraunhofer lines, they do not appear on the spectrum of the K-corona owing to insufficient concentrations of absorbing species exist in this region of the Sun.
In this work, Harkness' conclusion will be re-evaluated, with the intent of demonstrating that the K-corona is indeed self-luminous, as first postulated in 1869 [3, p.
It was the spectrum of the inner corona, or K-corona, which was measured long ago by Harkness, Young, and Evershed [2-4] and which has been the subject of several classic reports [5-10].
Superimposed on the continuous spectrum of the inner K-corona are emission lines, including one at 5303.3 A, the famous line from coronium, first discovered by Harkness and Young [2,3], photographed by Evershed [4], and eventually identified as FeXIV by Bengt Edlen [5-7].
Consequently, sufficient electron densities are inferred to exist in the corona to support the idea that the spectrum of the K-corona is being produced by the scattering of photospheric light: "The reason we see the corona in white, or integrated, light is that the photospheric light is scattered by coronal electrons: we see the light that does not get through but is scattered towards us.
Furthermore, by accepting elevated coronal temperatures, proponents of the gaseous models must discount the continuous emission of the K-corona as illusionary and produced by the photosphere (see [2] for a completed discussion).