CORONA 

  COVID---19

The article is about the plasma surrounding stars. For the colloquial term for the disease, see Coronavirus disease 2019. For other uses, see Corona (disambiguation).

During a total solar eclipse, the Sun's corona and prominences are visible to the naked eye.

A corona (meaning "crown" in Latin derived from Ancient Greek κορώνη (korōnè, "garland, wreath")) is an aura of plasma that surrounds the Sun and other stars. The Sun's corona extends millions of kilometres into outer space and is most easily seen during a total solar eclipse, but it is also observable with a coronagraph.

Spectroscopy measurements indicate strong ionization in the corona and a plasma temperature in excess of 1000000 kelvin,^[1] much hotter than the surface of the Sun.

Light from the corona comes from three primary sources, from the same volume of space.

The K-corona (K for kontinuierlich, "continuous" in German) is created by sunlight scattering off free electrons; Doppler broadening of the reflected photospheric absorption lines spreads them so greatly as to completely obscure them, giving the spectral appearance of a continuum with no absorption lines.

The F-corona (F for Fraunhofer) is created by sunlight bouncing off dust particles, and is observable because its light contains the Fraunhofer absorption lines that are seen in raw sunlight; the F-corona extends to very high elongation angles from the Sun, where it is called the zodiacal light.

The E-corona (E for emission) is due to spectral emission lines produced by ions that are present in the coronal plasma; it may be observed in broad or forbidden or hot spectral emission lines and is the main source of information about the corona's composition