Viktor Amazaspovich Ambartsumian

Born Sept. 5 (18), 1908, in Tiflis. Soviet astrophysicist working in the physics of stars and nebulae, astronomy, the dynamics of stellar systems, and the cosmogony of the stars and galaxies; founder of a school of theoretical astrophysics in the USSR. Academician of the Academy of Sciences of the USSR (1953; corresponding member, 1939); academician (1943) and president (1947) of the Academy of Sciences of the Armenian SSR; a professor at the University of Yerevan (1947). Became a Hero of Socialist Labor in 1968. Member of the CPSU since 1940.

Ambartsumian founded the quantitative theory of emission of gaseous nebulae, and proposed a method for calculating the masses that are ejected by nova stars and that flow out from the surfaces of nonstationary stars. He developed the fundamentals of the statistical mechanics of stellar systems, demonstrated that stellar clusters decay gradually through the loss of individual stars, and estimated their ages on that basis. In 1947 he discovered and investigated dynamically unstable, decaying stellar systems of a new type, which he termed stellar associations. The extreme youth of stellar associations established by Ambartsumian made it possible to solve some fundamental problems in stellar cosmogony. He found that interstellar absorption of light is caused not by the continuous medium but by discrete dark nebulae. He developed a special theory to aid statistical research on interstellar absorbing clouds. Ambartsumian developed a new theory of scattering of light in turbid media and a theory of baryonic stars possessing a density much greater than nuclear density. He established the cosmogonic activity of central clusters—nuclei of galaxies responsible for such grandiose nonstationary phenomena as colossal explosions, ejections of huge masses of materials, quiescent outflow of matter, and high-power radio-frequency emissions. The new trend founded by Ambartsumian has exerted a great influence on the development of astronomical science.

Ambartsumian founded the Biurakan Astrophysical Observatory of the Academy of Sciences of the Armenian SSR in 1946 and is its permanent director. He has been vice-president (1948–55) and president (1961–64) of the International Astronomical Union; he is a member of many foreign academies and scientific societies. In 1968 he was elected president of the International Council of Scientific Unions. Ambartsumian was a deputy to the Supreme Soviet of the USSR in its third through seventh sessions. He was twice awarded the State Prize of the USSR (1946, 1950). He has been awarded three Orders of Lenin, as well as other orders and medals of the USSR and medals of foreign scientific societies.