An Etymological Dictionary of Astronomy and Astrophysics
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An → emission line in the spectrum of the → solar corona caused by highly ionized metal ions; especially those of iron, such as the red and green lines at 6375 Å and 5303 Å [Fe X] (Fe⁹⁺ ion) and [Fe XIV] (Fe¹³⁺ ion), respectively. From their discovery in 1870 until 1939, it was believed that these → forbidden lines would be due to an unknown element, called → coronium. Ultraviolet and X-ray coronal lines are also detectable in stars.

→ coronal; → line.