Viktor Ambartsumian

First to study stellar radiation transfer in gaseous nebulae

Viktor Amazaspovich Ambartsumian was a Soviet Armenian astrophysicist and science administrator. One of the 20th century’s top astronomers, he is widely regarded as the founder of theoretical astrophysics in the Soviet Union.

Educated at Leningrad State University (LSU) and the Pulkovo Observatory, Ambartsumian taught at LSU and founded the Soviet Union’s first department of astrophysics there in 1934. He subsequently moved to Soviet Armenia, where he founded the Byurakan Observatory in 1946. It became his institutional base for the decades to come and a major center of astronomical research. He also co-founded the Armenian Academy of Sciences and led it for almost half a century—the entire post-war period. One commentator noted that « science in Armenia was synonymous with the name Ambartsumian. » In 1965 Ambartsumian founded the journal Astrofizika and served as its editor for over 20 years.

Ambartsumian began retiring from the various positions he held only from the age of 80. He died at his house in Byurakan and was buried on the grounds of the observatory. He was declared a National Hero of Armenia in 1994.

Education

Ambartsumian developed an early interest in mathematics and was able to multiply by the age of 4. His interest in astronomy began with reading a Russian translation of a book by Ormsby M. Mitchel at 11. According to himself, he became an astronomer at the age of 12. Between 1917 and 1924 he studied at Tiflis gymnasiums #3 and #4 where schooling was done in both Russian and Armenian. In 1921 he transferred to gymnasium #4 to study under Nikolay Ignatievich Sudakov, a Moscow-educated astronomer, whom Ambartsumian called a « very serious teacher of astronomy. » Ambartsumian worked with Sudakov at the school observatory the latter had built. At school, Ambartsumian wrote several papers on astronomy and delivered lectures on the origin of the Solar System and extraterrestrial life at « first in school and then in the various clubs and houses of culture » beginning at 12–13. In 1924 Ambartsumian delivered a lecture at Yerevan State University about the theory of relativity.

In 1924 Ambartsumian moved to Leningrad, where he began attending the Herzen Pedagogical Institute. In an interview Ambartsumian stated that it was too late for him to apply to Leningrad State University (LSU), because he arrived in August and admissions were already closed. Not to lose a year, he instead enrolled in the physics and mathematics department at the pedagogical institute. After a year, he transferred to LSU’s department of physics and mathematics. At university, Ambartsumian was interested in both astronomy and mathematics. « I loved mathematics, but at the same time I felt that my profession would be astronomy. Mathematics was like a hobby, but I did complete the full mathematics curriculum. Thus you could say that I graduated with a major in mathematics, but in fact it is recorded that I graduated as an astronomer, » he said in an interview in 1987. In 1926 he published the first of his 16 scholarly papers as a student. He graduated in 1928, although he received his diploma only fifty years later—in 1978. His undergraduate thesis was « devoted to a study of radiative transfer radiative equilibrium. » He completed his postgraduate studies at the Pulkovo Observatory under Aristarkh Belopolsky between 1928 and 1931.

Career

Leningrad

After completing his postgraduate studies in 1931, Ambartsumian began working at the Pulkovo Observatory and teaching part-time at LSU. In 1931 Ambartsumian began reading the first course on theoretical astrophysics in the Soviet Union. He also served as Pulkovo’s scientific secretary in 1931–32, which involved mostly administrative work.

After leaving Pulkovo, Ambartsumian founded the first department of astrophysics in the Soviet Union at Leningrad State University in 1934. In 1934 he was named professor at LSU and in 1935 he was named doctor of physical-mathematical sciences without having to defend a thesis « based on his scientific work through that date. » He headed the department until 1946 or 1947.

World War II

Ambartsumian led the evacuation of part of the faculty of Leningrad State University to Elabuga, Tatarstan in 1941, after the Nazi invasion of the Soviet Union. There a branch of LSU operated under Ambartsumian’s leadership until 1944. He served as the dean of the branch.

Armenia

In 1943 Ambartsumian moved with his family to Yerevan, Soviet Armenia, where he lived until the end of his life. In the same year, he co-founded the Armenian Academy of Sciences along with scientists and scholars Hovsep Orbeli, Hrachia Acharian, Artem Alikhanian, Abram Alikhanov, Manuk Abeghian and others. He served as vice president of the academy until 1947 and as president from 1947 to 1993.

Since 1943 Ambartsumian served as director of the Yerevan Astronomical Observatory. The small observatory was affiliated with Yerevan State University. Ambartsumian had secured a nine-inch telescope from Leningrad for the observatory. Ambartsumian said that before the war « this observatory did not rise significantly above the level of amateur variable star observations. During the war they also carried out photographic observations of variable stars using a small camera. » In 1945–1946 Ambartsumian founded the department of astrophysics at Yerevan State University (YSU). He was named professor of astrophysics at YSU in 1947. He served as chair of the department until 1994.

In 1965 Ambartsumian founded the journal Astrofizika (Armenian: Աստղաֆիզիկա, Russian: Астрофизика), which has been published by the Armenian Academy of Sciences since then. It was originally published in Russian, subsequently articles in English began to appear. He served as its editor-in-chief until 1987. The journal has also been published since the first issue in English by Springer in the US as Astrophysics.

Byurakan

In 1946 Ambartsumian founded the Byurakan Astrophysical Observatory in the village of Byurakan. The first buildings were completed in 1951, though the official inauguration took place in 1956. Observations began to be carried out simultaneous with the construction of the observatory. « Our instruments stood under the open sky, covered with tarpaulin, » said Ambartsumian. Ambartsumian initially lived at a house in the village of Byurakan then build a house within the observatory grounds with the money awarded with the 1950 Stalin Prize. Ambartsumian directed the Byurakan Observatory until 1988 and was named its honorary director that year. From 1946 until his death in 1996, the Byurakan Observatory served as Ambartsumian’s « institutional base. »

In 1968 the observatory was awarded the Order of Lenin, the Soviet Union’s highest civilian order for its great merit to the development of science. In 1961 Ambartsumian supervised the establishment of an astrophysical station of Leningrad State University, his alma mater, within the grounds of the Byurakan Observatory. It is where graduate students of the LSU did their summer internships until the late 1980s. It was shut down in 1993.

Ambartsumian and his disciples at the Byurakan Observatory became known in the scholarly literature as the « Byurakan School. » From 1977 to 1996 Ambartsumian headed a specialized council for theses defenses at Byurakan. Over 50 scientists defended their PhD (Candidate) and Doctoral theses on astronomy, astrophysics and theoretical physics in those years under Ambartsumian.

With the Byurakan Observatory, Ambartsumian « put Armenia on the astronomical map » and made Soviet Armenia « one of the world’s centers for the study of astrophysics. » By the time of his death in 1996, The New York Times described Byurakan as « one of the world’s leading astronomical research centers. » As of 1960 the Byurakan Observatory maintained regular contact with 350 research institutions and with scientists from 50 countries.

With the Byurakan Observatory, Ambartsumian « put Armenia on the astronomical map » and made Soviet Armenia « one of the world’s centers for the study of astrophysics. » By the time of his death in 1996, The New York Times described Byurakan as « one of the world’s leading astronomical research centers. » As of 1960 the Byurakan Observatory maintained regular contact with 350 research institutions and with scientists from 50 countries.

Research

Ambartsumian carried out basic research in astronomy and cosmogony. It covered astrophysics, theoretical physics and mathematical physics, and mostly focused on the physics of nebulae, star systems, and extragalactic astronomy. He is best known for having discovered stellar associations and predicted activity of galactic nuclei. In his later career, Ambartsumian held views in contradiction to the consequences of the general relativity, such as rejecting the existence of black holes.

Stellar association

In 1947 Ambartsumian discovered stellar associations, a new type of stellar system, which led to the conclusion that star formation continues to take place in the Milky Way galaxy. At the time the « idea of star formation as an ongoing process was regarded as very speculative. » His discovery was announced in a short publication by the Armenian Academy Sciences. Ambartsumian divided stellar associations into OB and T groups and concluded that the « associations have to be dynamically unstable configurations, and must expand subsequently, dissolving to form field stars. » He thus argued that star forming is ongoing in the galaxy and that stars are born explosively and in groups.

Active galactic nuclei (AGN)

Ambartsumian began studying nuclei of galaxies in the mid-1950s. He found that clusters of galaxies are unstable and that galaxy formation is still ongoing. At the 1958 Solvay Conference on Physics in Brussels he gave a famous report in which he emphasized the extraordinary character of the activity of galactic nuclei (AGN). He claimed « enormous explosions take place in galactic nuclei and as a result a huge amount of mass is expelled. In addition, if this is so, these galactic nuclei must contain bodies of huge mass and unknown nature. » Lynden-Bell and Gurzadyan note that Ambartsumian was « perhaps the first to emphasize explosive phenomena in galactic nuclei. » Evidence for the activity included the Markarian galaxies, discovered at Byurakan. The concept of AGN was widely accepted some years later, especially after quasars were discovered in 1963. Ambartsumian developed and summarized his views on activity of galaxies in the 1960s.

Radiative transfer

Ambartsumian discovered basic results in radiative transfer in astronomy. He was the first or one of the first to study stellar radiation transfer in gaseous nebulae. He devised techniques for calculating the rates of star cluster decay and the time needed to reach statistical equilibrium in double star systems.

Recognition

Ambartsumian was one of the 20th century’s leading astrophysicists and astronomers. He was the leading astronomer of the Soviet Union and is universally recognized as the founder of the Soviet school of theoretical astrophysics. Ambartsumian was also well-regarded internationally. He was an honorary or foreign member of academies of sciences of over 25 countries.

Despite being a Soviet scientist, he was well-regarded in the United States. During the Cold War, Ambartsumian was the first Soviet scientist to become foreign honorary member of the American Academy of Arts and Sciences and foreign associate of the National Academy of Sciences in 1958 and 1959, respectively. In January 1971 Ambartsumian was invited to the U.S. House Committee on Science and Astronautics, where he was introduced by Fred Lawrence Whipple as a « man who is rated the world’s greatest astronomer or at least among the very greatest. »

In Armenia

After he visited Byurakan for the First Soviet-American Conference on Communication with Extraterrestrial Intelligence in 1971, William H. McNeill wrote that Ambartsumian is a « world famous astronomer and a man of enormous local prestige. » One of the « modern icons of Armenian pride, » Ambartsumian is recognized as the most prominent scientist in 20th century Armenia, and possibly the greatest since the seventh century polymath Anania Shirakatsi.

Tribute

An asteroid discovered at the Crimean Astrophysical Observatory in 1972 by Tamara Smirnova is named 1905 Ambartsumian.

In 1998 Ambartsumian’s 90th anniversary was celebrated in Armenia; the International Astronomical Union held a symposium at the Byurakan Observatory and the Central Bank of Armenia issued a 100 dram banknote depicting Ambartsumian and the Byurakan Observatory. The Byurakan Observatory was officially named after Ambartsumian that year. Other things named after Ambartsumian include Chair of General Physics and Astrophysics at Yerevan State University, a street, park, and public school in Yerevan, and the Pedagogical Institute of Vardenis.

In 2009 a bronze statue of Ambartsumian was unveiled in Yerevan at the park around the Yerevan Observatory. Busts of Ambartsumian stand at the Byurakan Observatory, the city of Vardenis (1978), and at the central campus of Yerevan State University.

Viktor Ambartsumian International Prize

In 2009 President of Armenia Serzh Sargsyan signed a decree to establish an international prize in Ambartsumian’s memory. It was first awarded in 2010 and is awarded every two years. The prize was initially $500,000, but was reduced to $300,000 in 2018. It is considered one of the prestigious awards in astronomy and related fields.

Awards and honors

State awards

Soviet Union

• Honored Scientist of the Armenian SSR (1940) and the Georgian SSR (1968)
• Order of Lenin (1945, 1958, 1974, 1978)
• USSR State Prize (1946, 1950)
• Order of the Red Banner of Labour (1953)
• Medal « For Labour Valour » (1960)
• Hero of Socialist Labour (1968, 1978)
• Order of the October Revolution (1983)

Armenia

• National Hero of Armenia (1994)

Foreign countries

• Order of Cyril and Methodius, People’s Republic of Bulgaria (1969)
• State Prize of the Russian Federation (1995)

Professional awards

• Janssen Prize (Prix Jules-Janssen) of Société astronomique de France (1956)
• Gold Medal of the Royal Astronomical Society (1960) « for outstanding contributions to astrophysics »
• Bruce Medal of the Astronomical Society of the Pacific (1960)
• Lomonosov Gold Medal of the Soviet Academy of Sciences, « for outstanding achievements in the field of astronomy and astrophysics » (1971)
• Helmholtz Medal (Helmholtz-Medaille) of the Academy of Sciences of the German Democratic Republic (1971)
• Cothenius Medal (Cothenius-Medaille) of the Academy of Sciences Leopoldina (1974)

Membership

Soviet Union

• Corresponding Member of the USSR Academy of Sciences (1939)
• Full member (Academician) of the Armenian SSR Academy of Sciences (1943)
• Full member (Academician) of the USSR Academy of Sciences (1953)
• Honorary member of the Academies of Sciences of the Georgian SSR and Azerbaijan SSR

Abroad

Ambartsumian was elected honorary and foreign member of 28 Academies of Sciences, including:

• Honorary Member of the American Astronomical Society (1947)
• Associate of the Royal Astronomical Society (1953)
• Corresponding member (1958) and foreign associate (1978) of the French Academy of Sciences
• Foreign Honorary Member of the American Academy of Arts and Sciences (1958)
• Foreign Associate of the U.S. National Academy of Sciences (1959)
• Honorary Member of the Royal Astronomical Society of Canada (1959)
• Foreign Member of the Royal Society (1969)

Honorary degrees

Ambartsumian received honorary doctorates from several universities: Australian National University (1963), University of Paris (1967), University of Liège (1967), Charles University in Prague (1967), Nicolaus Copernicus University in Toruń (1973), National University of La Plata (1974).