Corona radiation emission

Emission lines also occur in stellar radiation, especially from hot stars, e.g. from Wolf-Rayet stars. In the solar corona, emission lines from very highly ionized atoms occm. Several of these lines that are observed in the visible or UV regions correspond to forbidden transitions within the ionic ground configuration. For example, the 530.3 imi line is due to 13-fold ionized iron. The coronal lines constituted a long-lasting puzzle, which was solved by... 

Even for cooler stars, such as our sun, UV measurements are important for detecting and characterizing energetic phenomena that occur in their outer atmospheres. For the sun, these include the high-temperature solar corona, solar flares, and other manifestations of solar activity. Also, solar UV radiation is largely responsible for the maintenance of the terrestrial and other planetary ionospheres and for exciting UV emissions observed in planetary atmospheres and in comets. 

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