Edlén, Bengt

Born Ringarum, Östergötland, Sweden, 2 November 1906

Died Lund, Sweden, 10 February 1993

Swedish spectroscopist Bengt Edlén solved a 70‐year‐old puzzle by identifying emission lines in the solar corona (discovered in 1869 by Thomas Young) with transitions in very highly ionized atoms, thereby demonstrating that the corona is much hotter than the visible surface of the Sun. He received his secondary education in Norrköping, Sweden, and entered the University of Uppsala in 1926, earning a series of degrees ending with a doctorate in 1934.

By 1925, optical spectroscopy had reached a shortest wavelength of 155 Å, while X‐ray spectroscopy had reached a longest wavelength of 17 Å. Karl M. G. ("Manne") Siegbahn of Uppsala, who had received the 1924 Nobel Prize in Physics for his work on X‐ray spectroscopy, suggested that Edlén should try to fill in the gap. This led to a doctoral thesis on the ultraviolet spectra of light elements from lithium to oxygen, with wavelength