Swedish astrophysicist who resolved the identification of certain lines in spectra of the solar corona that had misled scientists for the previous 70 years.
Edlén was born in Östergötland and educated at Uppsala University, where he was on the staff 1928-44. He was professor of physics at Lund University 1944-73.
During the eclipse of 1869, astronomers recorded unexpected spectral lines in the Sun's corona that they ascribed to the presence of a new element which they called 'coronium'. Similar lines were later discovered to originate nearer the Earth; these were attributed to 'geocoronium'.
In the early 1940s, Edlén showed that, if iron atoms are deprived of many of their electrons, they can produce spectral lines like those of 'coronium'. Similarly ionized atoms of nickel, calcium, and argon produced even more lines. It was determined that such high stages of ionization would require temperatures of about 1,000,000°C/1,800,000°F and when, in the 1950s, it was verified that such high temperatures did exist in the solar corona, it became accepted that 'coronium' did not exist.
The lines thought to be caused by 'geocoronium' were found to be produced by atomic nitrogen emitting radiation in the Earth's upper atmosphere.