Albrecht Unsold (1905-1995)

Albrecht Unsold, the ASP's Bruce Medalist for 1956, passed away on September 23, 1995, at the age of 90. He was most famous for his contributions to the theory of stellar atmospheres and he trained a whole generation in this field. He soon applied what he had learned in atomic physics in the early 1920s to astrophysics, first to the solar spectrum, later on to stellar spectra in general. Curve-of-growth and fine-analysis methods were developed and, with improved broadening theories, paved the way for reliable abundance determinations. His monograph Physik der Sternatmospharen, first published in 1938, was considered a ''bible for astrophysicists'' for decades. Later he concerned himself with the interpretation of stellar abundances especially with respect to the origin of the elements. His introduction to astrophysics, The New Cosmos, appeared in several editions from 1967 to 1991 and was translated worldwide. A final book was devoted to the general concept of evolution in astronomy, biology, and the human mind.