# Victor Amazaspovich Ambartsumian

### Quick Info

Born
18 September 1908
Tiflis, Russian Empire, now Tbilisi, Georgia
Died
12 August 1996
Byurakan, Armenia

Summary
Viktor Ambartsumian was an Armenian astrophysicist who was born in what is now Georgia. He was one of the founders of theoretical astrophysics and worked in the field of the physics of stars and nebulae.

### Biography

Soviet Armenian astrophysicist Victor Amazaspovich Ambartsumian (Viktor Hamazaspi Hambardzumyan) was born on 18 September 1908, old style 5 September 1908, to an Armenian family, in Tiflis, now known as Tbilisi, the capital of Georgia. His father, Amazasp Asaturovich Ambartsumian, was a philologist, who was responsible for a translation of Homer's Iliad into Armenian. He undertook research on the historical development and relationship of languages and became a professor at Yerevan University. Victor's mother was Ripsame Ambartsumian. Victor was one of three children, having an older sister who became the chairman of the Department of Probability Theory at Yerevan University and a younger brother who died at the age of 23 while working on a geophysical expedition as an operator.

It was Amazasp who encouraged the development of Victor's aptitude for mathematics and physics. He [28]:-
... even showed off to his friends that he had such a son who could already multiply when he was all of three or four years old.
By the time he was of an age to begin his formal schooling in the junior preparatory class, he had to sit a test before being accepted. Given an arithmetic problem he could easily do in his head, he wrote down the correct answer. He was failed and when his father angrily (Victor said his father was a hot-headed man) demanded to know why his son had been failed he was told that the problem was a hard one and all steps of the working were necessary. Victor's father then said he would teach his son himself and he would go straight into the senior class. This is what happened and after two years, during which time he learnt Russian, he entered the first class of the Gymnasium.

Ambartsumian loved mathematics and became interested in astronomy at the age of twelve after reading a Russian translation of The Planetary and Stellar Worlds (1848) by Ormsby McKnight Mitchel (1809-1862). The Russian translation, published in 1859, was entitled The Celestial Bodies, or Planetary and star worlds. Popular exposition of the great discoveries and theories of modern astronomy (Russian). His teacher at the Gymnasium wrote on one of his reports, "this boy can become in future the founder of an astronomical observatory in Armenia." Ambartsumian gave lectures on astronomy while at the Gymnasium and, discovering that a Moscow trained astronomer Nikolai Ignatevich Sudakov was teaching at another Tiflis school he transferred there. Ambartsumian completed the Gymnasium courses rapidly and graduated before his sixteenth birthday. Following his father's advice, he decided to study at the University of Leningrad, a good choice since the Pulkovo Observatory was close to the city.

Arriving in Leningrad too late in 1924 to enter the University of Leningrad in that year, he studied in the Mathematics and Physics department of the Herzen Pedagogical Institute for eighteen months. In 1925, Ambartsumian entered into the University of Leningrad (what is now known as the St Petersburg State University), as an undergraduate, hoping to devote his life's work to the research of astrophysics. One of his fellow undergraduates was Sergei L'vovich Sobolev who specialised in mathematics. Other student friends included Lev Davidovich Landau and George Gamow (1904-1968). Ambartsumian published a paper devoted to sun jets in 1926, Eine Methode der Bestimmung der Hole der Sonnenfackeln nach der Veranderung ihrer Helligkeit , the first of ten papers that he would publish as an undergraduate. This 1926 paper was a joint work with his fellow student Nikolai Alexandrovich Kozyrev (1908-1983). Recalling his student years he said [25]:-
During my studies at the University of Leningrad I paid chief attention to astronomy and mathematical courses. While I always felt the necessity of a better knowledge of physics, at that time this discipline did not attract me much. It is true that during my last two university years the logical beauty of quantum mechanics as well as some aspects of statistical physics deeply impressed me.
Graduating in 1928, he went on to continue his studies as a postgraduate at the Pulkovo Observatory near Leningrad (now St Petersburg), under the supervision of Aristarkh Apollonovich Belopolsky (1854-1934) who had worked at Pulkovo Observatory from 1888. Ambartsumian continued to undertake research at the Observatory until 1931.

An early step on his road to recognition was taken with his paper, Über eine Folgerung der Diracschen Theorie der Protonen und Electronen written jointly with Dmitri Dmitrievich Ivanenko (1904-1994) in 1929. Ivanenko was, at this time, working at the Physical Mathematical Institute of USSR Academy of Sciences in Leningrad. Their publication showed that the atomic nucleus could not be made up of protons and electrons. This was soon confirmed, when three years later, Sir James Chadwick discovered neutrons, which, together with protons, make up atomic nuclei.

He married Vera Feodorovna Klochihina (born at Lisva, Solikamsk uyezd, Perm) in 1931 and joined the Communist Party of the USSR in 1940.

He spent the years 1931-43 lecturing at the University of Leningrad, heading the astrophysical department. It was in 1932 that Monthly Notices of the Royal Astronomical Society published his paper "On the radiative equilibrium of a planetary nebula", now considered a cornerstone of the modern theory of the gas nebulae. This led to a series of research articles developing the topic further. After three years' affiliation with Leningrad University, Ambartsumian founded and headed the first astrophysics chair in 1934, making him a professor at the university.

For the problems at the Pulkovo Observatory during the 1930s, see THIS LINK.

In 1938 he came up with the first idea about the patchy structure of interstellar absorption. Chandrasekhar writes in [12]:-
Ambartsumian's marvellously elegant formulation of the fluctuations in brightness of the Milky Way in the limit of infinite optical depth, showed that the probability distribution of the fluctuations in the brightness of the Milky Way is invariant with the respect to the location of the observer.
The War years provided obstacles for Ambartsumian and his work. Having served as director of the Leningrad University Observatory between 1938 and 1941, he and the laboratories of the University were relocated to the remote Yelabuga, Tatarstan in west Russia in 1941. This relocation was, of course, forced because of German forces advancing towards Leningrad. Ambartsumian spent four years there directing the work of the laboratories working both on military problems and on the scattering of light. Between 1941 and 1943, Ambartsumian was appointed pro-rector of the University, and while in this role he developed his theory of the behaviour of light in a scattering medium of cosmic space. This became an important tool in geophysics, space research and particularly astrophysics.

The Armenian Academy of Sciences was founded on 10 November 1943 as a branch of the USSR Academy of Sciences. Ambartsumian returned to Armenia to become the first vice-president of the new Academy. In addition, in 1944 he founded the first chair of Astrophysics at Yerevan University and was appointed as director of the Yerevan Observatory.

In 1946, he organised the construction of the Byurakan Astronomical Observatory 30 km from Yerevan, the capital of Armenia. This site was well chosen at a height of 1500 metres above sea level on Mt Aragats. Here he began another successful period of activity as the director of the observatory, a role he would maintain until 1988 [25]:-
While the construction of the Observatory was proceeding, a small group of young astronomers (including Benjamin Markarian, Hayk Badalyan and a student Grigor Gurzadyan) started observations with very modest facilities. They had to design or even build many instruments themselves. In later years the Observatory supplied both telescopes and other facilities, and the students came mainly from the graduates of the astrophysical department of Yerevan University. The official inauguration of the Observatory took place in 1956, marked by a symposium with the participation of numerous astronomers from all over the world. Ambartsumian made Byurakan an internationally known scientific centre. In conditions when the communications with the West were rather complicated (the cold war years) he managed to link Byurakan by active bilateral collaboration with the Abastumani Observatory in Georgia, with observatories in Bulgaria, Hungary, Eastern Germany, Romania and Czechoslovakia. Among his students were those from Russia, Georgia, Ukraine, Azerbaijan, Hungary, Bulgaria, etc. However, even in those conditions several International Astronomical Union (IAU) Symposia and numerous conferences with participation of western scholars were held in Byurakan.
By 1947, he had discovered a new type of comparatively recent stellar system, which he named "stellar association" [27]:-
This concept, which involves the interrelationships between great complexes of gas, dust, and stars, like the region of the Orion Nebula, has proven invaluable in our efforts to understand the processes of star creation and development. Ambartsumian's work in this fascinating field has undoubtedly been one of the most powerful influences in stimulating modern research on stellar evolution and galactic structure.
Chandrasekhar, who had first met Ambartsumian in 1935, recalled many years later (see [27]):-
I recall the early scepticism with which this discovery was received by the astronomers of the 'establishment' when I first gave an account of Ambartsumian's paper at the colloquium at the Yerkes Observatory in late 1950.
The most important of his results concluded that the process of stellar formation in the Milky Way still continues and that most stars have their origin in developing systems of groups of stars.

Ambartsumian also studied radio signals coming from outside the Milky Way. His conclusion of these studies contradicted the widely accepted interpretation of the time, that these radio signals are received from star system collisions. Instead, he forwarded the idea that the signals were due to the subatomic process of fission within galaxies. Thus, according to his view, 'radio galaxies' may represent systems of stars interacting in close proximity, that were formed from super-dense formations of stellar material.

His textbook Theoretical Astrophysics, published in 1958, went through many editions and translations, containing examples of his unique approaches to difficult astronomical problems. Moreover, he is credited with having a popular and engaging lecturing style, drawing large audiences at international symposia. He is known to have added in poetic quotes to even his most mathematical addresses.

Throughout his career, he was made a member of many academic societies and academies, establishing himself considerably in them. He was elected in 1939 as a corresponding member of the USSR Academy of Sciences, becoming a full academician in 1953. He was appointed founding vice-president of the Armenian Academy of Sciences in Yerevan in 1943, under the presidency of Joseph Orbeli. He began teaching at the Yerevan State University.

Ambartsumian succeeded Orbeli and became the longest serving president of the Academy, heading it from 1947 to 1993. Following this reign, he was made an Honorary President of the Academy. He served as president of the International Astronomical Union from 1961 to 1964, and was twice elected the president of the International Council of Scientific Unions serving between 1966 and 1972, having previously worked as vice-president (1948-1956). Adriaan Blaauw writes [9]:-
Ambartsumian's term as a Vice-President of the International Astronomical Union coincided with the years of the cold war between the western powers and the Soviet Union. In those years, the International Astronomical Union went through a critical stage in its existence as a consequence of the International Astronomical Union Executive Committee's decision to postpone the General Assembly that had been planned for 1951 in Leningrad. During the subsequent years, although vigorously contesting the Executive Committee's decision, Ambartsumian did not fail to continue his support to the Union as the world-wide organisation embracing astronomers from all countries. His election as President of the International Astronomical Union in 1961 reflected both the appreciation for his efforts in this respect and his outstanding scientific achievements.
He was also a foreign member of many societies, including the Royal Society in Britain, the National Academy of Sciences in the United States, and the Indian Academy of Sciences.

Additionally, he received many awards for his services to science. Twice the recipient of the Stalin Prize (1946, 1950), once the Gold Medal of the Royal Astronomical Society (1960), once the Bruce Gold Medal of the Astronomical Society of the Pacific (1960), he also received the Hero of Socialist Labour award (1968, 1978), and the National Hero of Armenia award (1994). These are only a few of the numerous honours bestowed on him.

A minor planet discovered in May 1972 by T M Smirnova at the Crimea Observatory was named after Ambartsumian (1905 Ambartsumian).

On Ambartsumian's 80th birthday, Subrahmanyan Chandrasekhar wrote [12]:-
The only other astronomer of this century who compares with Academician Ambartsumian in his consistency and devotion to astronomy is Professor Jan Oort. ... There can be no more than two or three astronomers in this century who can look back on a life so worthily devoted to the progress of astronomy.
Ambartsumian died on 12 August 1996 in Byurakan, and is buried next to the Grand Telescope Tower there.

For the first time in 2010, the Viktor Ambartsumian International Prize was awarded. Set up by the President of the Republic of Armenia, the award is granted to those offering outstanding contributions in the field of astrophysics and in adjacent scientific fields such as mathematics and physics. It is awarded biennially, and until 2016, was worth $500,000. At present (2018)$300,000 is awarded with the Prize.

### References (show)

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