Theoretical astrophysics, stellar dynamics, exoatmospheric astronomy, matters of stars and galaxies evolution

Graduated from LSU (1928). Doctor of Phys. and Math. Sciences (1935), prof. (1934), acad. (1943), acad of USSR NA (1953, corr. member 1939)

LSU prof. (1934-1944). Vice-president of NA of Soviet Socialist RA (1947-1993), president (1947-1993), director and founder of BAO of NAS RA (1946-1996)

Member of more than 20 national academies. Vice-president of the International Astronomical Union (1948-1955), President of (IAU) (1961-1964), President of the International Council of Scientific Unions (ICSU) (1968-1972)

Twice Hero of Socialistic Labour, USSR State Prises, awarded Lenin (5), October Revolution, Red Banner of Labour (2) medals, M.Y. Lomonosov, I. Vavilov, H. Helmholts medals