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
The lines thought to be caused by 'geocoronium' were found to be produced
by atomic nitrogen emitting radiation in the Earth's upper atmosphere.