MacTutor
Within the Soviet Union Victor Ambartsumian pursued twin careers as both a leading astronomer and a powerful politician who rose to represent his native Armenia as a deputy in the Supreme Soviet of the USSR.
Ambartsumian was born prematurely on 18 September 1908 on arrival in Tbilisi, Georgia, when his parents were journeying from Armenia on their way to St Petersburgh. His father was a specialist in Greek philosophy and literature and translated Homers works into Armenian. He paid particular attention to the education of his children, a son and a daughter followed by Victor. Victor showed an early interest in the natural world and in mathematics. In a document that survives from 1918 his school teacher, when requesting support for his 10 year old pupil, made the extraordinary prediction that this boy can become in future the founder of an astronomical observatory in Armenia.
In Leningrad University (1925-1928) Ambartsumian joined a core of gifted undergraduates renowned not only for their science but also for their practical jokes. This group included George Gamow, Lev Landau, Matvey Bronstein and Nikolay Kozirev. In 1928 he moved to work for his doctorate on stellar and nebular atmospheres at Pulkovo Observatory. He had a life-long respect for his supervisor Aristarkh Belopolsky whose portrait always hung in his office. In 1929 Ambartsumian solved the inverse Sturm-Liouville problem, namely the recovery of the differential operator from its eigenvalues. This paper laid the foundation for the modern theory of Inverse Problems.
In 1936 he argued from the statistics of double stars against Jeans long timescale of 1013 years and in favour of the 1010 year timescale. Later he calculated the rate of evaporation of stars from star clusters, thus laying the foundation for the theory of their evolution.
In the period 1935-1940 Soviet politics led to serious disruption of the work at Pulkovo. First, Numerov the director was arrested for antiSoviet activities. Later Gerasimovich became director. Past history had already led to enmity between him and Ambartsumian and this came to a head during his directorship. On his dismissal from the observatory, Ambartsumian moved to the University of Leningrad where he became Professor of Astrophysics. The difficulties of working in an international subject under a totalitarian rgime are only too well illustrated by the executions of both Numerov and Gerasimovich, while Ambartsumian had to exercise all his political talents to avoid being caught up in the extension of that net.
In 1941 the German army besieged Leningrad so the University along with other academic institutions were evacuated to Elabuga in Tatarstan. Here Ambartsumian discovered the invariance principles in the theory of radiative transfer. These were later taken up and developed by Chandrasekhar with whom Ambartsumian had a long lasting relationship.
Thus he was already well known internationally when in 1943 he moved back to his native Armenia. Here in 1944 he founded the worldfamous Byurakan Observatory on Mount Aragats, north of the Armenian capital Yerevan. He was president of the Armenian Academy of Sciences from 1947 to 1993, and Professor of Astrophysics at Erevan University.
Expanding associations
He developed the idea that explosions from a very dense state are associated with the formation of stars, star clusters, galaxies and even the universe itself. He showed that most young stars are not gravitationally bound in clusters but are members of expanding associations, and this was soon widely accepted. He regarded this expansion as a relic of the creation process, and looked for explosions as a sign of creation in all astronomical objects from flare stars to galaxies and the universe.
Explosions in galactic nuclei and quasars are now widely accepted phenomena and while these were certainly predicted by Ambartsumians ideas, those ideas themselves are not widely held. Nevertheless it was his relentless quest to get evidence to further these ideas concerning astronomical explosions that led him to push for better equipment for the observatory.
He directed campaigns of discovery and observation of many of the most interesting objects in the sky, including flare stars in clusters and associations, active galaxies and quasars. Without the equipment he fought for, such well-known astronomical catalogues of active galaxies as those of Markarian and Arakelian would never have been produced, and Gurzadians studies of flare stars could not have been made. Later Byurakan produced Orion 2, the ultraviolet Cassegrain telescope with an objective prism flown on the manned Soyuz 13. Stars as faint as 13 m were observed.
Ambartsumian put Armenia on the astronomical map. He could never have achieved all this without his skills as a politician. From 1940 he was a member of the Communist Party of the Soviet Union. He served as a Deputy to the Supreme Soviet of the USSR from 1950, and was a member of the foreign affairs committee of the Soviet Union as well as holding similar posts in the Armenian Communist Party. In 1990, aged 82, he went on a three-week hunger strike to attract the Soviet governments attention to the violation of human rights in the Nagorno-Karabach Armenian enclave of Azerbaijan.
He was twice a Hero of Soviet Labour and held the Hammer and Sickle Gold Medal and five Orders of Lenin amongst other Communist awards. He was president of the International Astronomical Union 19611964 and of the International Council of Scientific Unions 1968-1972.
His many academic honours include membership of the USSR Academy of Sciences in which he was highly influential, and foreign membership of the Royal Society, the US National Academy and the Indian Academy of Sciences. After the collapse of the Soviet Union he was awarded the medal of a National Hero of Armenia.
He became a Foreign Member of the Royal Society in 1969, was made an Associate of the RAS in 1953, and was the Gold Medallist and George Darwin Lecturer in 1960.
Victor Ambartsumian was a broad-shouldered thick-set man of medium height, quick intellect and strong character. It was best to have him on your side in any argument. His love of poetry and music was shared with his wife Vera, whom he married in 1931. She was the adopted daughter of Academician Gregory Shain (director of the Crimean Observatory). They had two sons and two daughters who survive them. She died in 1995. He died in Byurakan Observatory on 12 August 1996.
D Lynden-Bell, V Gurzadian.
Victor Ambartsumian's obituary appeared in Astronomy & Geophysics 38:2 (1997), 37.