Aksel Kipper
Aksel Kipper was an Estonian astrophysicist and academician, known for theoretical work on the continuous spectra of planetary nebulae and for his role in establishing the modern Tartu Observatory at Tõravere.
Early life and education
Kipper was born in Viljandi. He graduated from the Viljandi boys’ gymnasium in 1926 and studied at the University of Tartu. After graduating in 1930, he defended a master's thesis on the open cluster Messier 39. He defended his doctoral dissertation, Gaasi liikumisest pulseeriva tähe atmosfääris, in 1938.Career and institutional leadership
Kipper began working at the Tartu observatory in 1930 and later became a professor at the University of Tartu. After 1944 he held senior academic and administrative roles at the university, including deputy pro-rector for studies, and headed physics-related departments in the mid-1940s.In 1946 he was elected a founding academician of the Academy of Sciences of the Estonian SSR and served as its vice-president until 1950. In 1950 he became director of the Institute of Physics, Mathematics and Mechanics, which was reorganised into the Institute of Physics and Astronomy in 1952; he served as director until 1973.
During his directorship, Kipper was a principal organiser of the modern observatory complex at Tõravere, built to replace the ageing city-centre facilities; it opened in September 1964 and became Estonia's main centre for astronomical research. Following institutional reorganisation in 1973, he became the first director of the Institute of Astrophysics and Atmospheric Physics in Tõravere and retired from the post in 1974, continuing research work thereafter.
Scientific work
Kipper's research included the physics of stellar atmospheres and pulsating stars, including work on shock-wave formation in stellar outer layers.He is especially noted for explaining the origin of the continuous spectrum of planetary nebulae using two-photon processes in hydrogen and related radiative-transfer effects, publishing key works in 1950 and 1952. In later decades he worked on magnetohydrodynamical processes in stars and developed ideas on turbulence in cosmic magnetic fields; in his final period he turned to cosmological questions involving electromagnetic and quantum properties of cosmological space and their relation to redshift phenomena.
Awards and honours
Kipper joined the International Astronomical Union in 1955. He received the honorary title of Merited Scientist of the Estonian SSR in 1957 and the Nõukogude Eesti preemia in 1967. He was awarded the Karl Ernst von Baer medal in 1976.He was decorated with the Order of the [Red Banner of Labour] and the Order of the Badge of Honour.