|Victor Amazaspovich Ambartsumian (5(18) September 1908, Tiflis -12 August 1996, Byurakan). Outstanding soviet scientist, one of the founders of the theoretical astrophysics, Amabartsumian worked in the field of physics of stars and nebulae, stellar astronomy, dynamics of stellar systems and cosmogony of stars and galaxies, contributions to Mathematical physics. Stalin prize (1946,1950), Socialist Labor Hero (1968,1978) , Russian Federation State prize (1995), National Hero of Armenia, numerous academic awards, founder of Byurakan observatory.
1 — Biographical note.
Ambartsumian was born to an Armenian family in Tiflis 5(18) September 1908. His father was philologist and writer Hamazasp Asaturovich Amabartsumian, translator of Homer’s Iliad into Armenian. In 1924 Victor entered physico-mathematical department of Pedagogical Institute in Leningrad and then of Leningrad University. As astudent he published in 1926 his first scientific article devoted to the sun flears. Amabartsumian continued his postgraduate studies at Pulkovo Observatory under the guidance of professor A.A.Belopolskij in1928-1931.
In 1930 married Vera Feodorovna Ambartsumian(nee Klochihina, born at Lisva of Solikamsk uezd, Perm).
After three years of affiliation at Leningrad University Ambartsumian in 1934 founded and headed the first astrophysics chair. In 1939-1941 Amabrtsumian was the director of the Leningrad University Observatory.
In 1939 Ambartsumian was elected a correspondent member of the Academy of Sciences of the USSR. In 1953 he became a full academician of the Academy.
The War found him holding the position of the pro-rector of Leningrad University. The scientific laboratories of the University were evacuated in 1941 to remote Elabuga (Tatarstan) where Ambartsumian spent four years directing the work of the refugee laboratories.
In the heaviest period of the war, in 1943 the Academy of Sicence of the Armenian SSR was founded. Probably, this was a reword Armenia received for her loyalty to the Soviet Union in the great war affort. I.A.Orbeli was appointed as psident and Ambartsumian the vice–psident of Armenian Academy. In 1947 Ambartsumian was elected the psident of the Armenian Academy and since then he was invariably reelected to hold position for all terms till 1993. In 1993 he became the Honorary President of the Armenian Academy.
In 1946 the Byurakan Astrophysical Observatory was founded. Ambartsumian became the first its Director and he directed the Observatory till 1988.
Amabartsumian was the President of the International Astronomical Union from 1961 till 1964. He was twice elected the President of the International Council of Scientific Unions (1966-1972).
V.A. Amabartzumian died in August 1996 in Byurakan and is buried next to the Grand Telescope Tower.
Physics of stellar shells and gas nebulae.
In 1932 “Monthly Notices” of the Royal Astronomical Society published a paper by V.A.Amabrtsumian “On the radiative equilibrium of a planetary nebula” nowdays considered to be the corner-stone of the modern theory of the gas nebulae. In a series of research articles by stars,nebulae,galacAmabrtsumian that topic was developed further. In one of these articles Ambartsumian (with N.A.Kozyrev) managed to evaluate for the first time the masses of the gas shells ejected by the novas. Elaborate methods were applied in the research of gas shells of the non-stationary stars. The evaluations of the masses proved significant in the problems of the stellar evolution. In particular they resulted in the identification of the symptoms of the pending changes in the life of a star. Ambartsumian lay the basis of the theory of the star shells and gas nebulae and explained many particularities of their spectra.
Dynamics and statistical mechanics of the stellar systems.
In 1936 Ambartsumian gives an elegant solution of mathematical problem posed by the famous British scientist [[Arthur Eddington]]: determination of the distribution of the stars spatial speeds basing on the distribution of their radial speeds. The solution was
published in the “Monthly Notices” by recommendation of Arthur Eddington himself. Decades later the same mathematical problem reappered in the context of [[medical computer diagnostic]]s. Eventually (1979) that mathematical topic was marked by the Nobel Prize in medicine “For the development of computer assisted tomography”. The research conducted by Ambartsumian in the stellar systems statistics and dynamics laid the foundations of the statistical mechanics of the stellar systems. For this particular contribution Ambartsumian was rewarded with the State Prize of Russian Federation in 1995.
In 1935 -1937 Ambartsumian in a polemics with a selebrated British scientist James Jeans as regards the age of our stellar system — the Galaxy, proved that our Galaxy is at least by 1000 times younger than the estimate given by Jeans and accepted by the scientific community.
The nature of the inter-stellar matter and theory of fluctuations.
A series of Ambartsumians articles is dedicated to the research of inter-stellar matter in the Galaxy. Ambartsumian puts forward an entirely new concept, that the light absorption in the Galaxy is caused by the psence of numerous dust nebulae or “absorbing clouds” in the inter-stellar space. Based on this concept of patchy structure of the inter-stellar absorbing matter the fluctuation theory was developed, which became a new direction in the astronomy.
The theory of light diffusion in turbid medium.
During the years of the World War II Amabrtsumian created a new theory of light diffusion in turbid media, based on invariance principle invention of his own. Using that mathematical tool Amabrtsumian resolved a number of nonlinear problems of the light diffusion. The invariance principle is psently widely applied in the different divisions of mathematical physics. In their book ‘Invariant Imbedding. Radiative Transfer in Slabs of Finite Thickness’ R.E.Bellman, R.E.Kalaba and M.C.Prestrud write that “As a result of this pioneering work, new analitic treatments were made available and simplified computational solutions were obtained. These ideas were further developed and extensively generalized by Chandrasekhar in a series of fundamental papers and in 1950 in his book… Many otherwise intractable problems were tamed, and great adwances were made”. (American Elsevier Publishing Co., 1963, p1.) In 1946 for the creation of the theory of lights diffusion in turbid media Ambartsumian was awarded his first Stalins Prize.
The stellarassociations,evolution associations and the stars evolution.
Ambartsumians theoretical analysis based on of the observational material for stellar systems belonging to our Galaxy resulted in a discovery of a new type of stellar systems. These expanding systems endowed with a positive energy he named “stellar associations” and proved their relatively young age. This proved to be a revolutionary basis in stellar cosmology, since it implied that the star formation process in the Galaxy is going on even today and the stars are born in groups. In 1950 Amartsumian was awarded his second Stalin Prize for the discovery and the research of the new type of stellar systems.
The physics of the young stars and the stellar energy sources.
No less interesting are the results of Amabartsumian’s research in the so called continuous emission, observed in the spectras of the young stars of the TAU Taurus type and their satellite non-stationary stars. This research led to important conclusions as regards the nature of the stellar energy sources. Amabartsumian proposed principally new concept of p-star matter, based on his research of stellar associations. As opposite to the classical hypotheses suggesting that the stars have been formed as a result of condensation of diffuse matter, the new hypothesis postulated the existence of massive bodies, the “proto-stars”. The process of disintegration of proto-stars is responsible for the formation of the stars in the associations.
Ambartsumian dedicated much research to the evolution of the galaxies — huge stellar systems resembling our Galaxy. He authored the new concept of activity of the galactic nuclei (cores, central condensations), to have a decisive role in the genesis and evolution of the galaxies and their systems. Owing to that vision, the study of the grand scale non-stationary phenomena, observed in the galaxies became the central subject of the extra-galaxy astronomy. An important research of Amabartsumian and his followers was dedicated to the blue ejections from the nuclei of the gigantic galaxies, galaxy systems of new type, the so called compact galaxies, etc. Ambartsumian’s first Solvay lecture, delivered in 1958, concerning the explosion of nuclei of the galaxies, was groundbreaking. That first lecture and the development it starts were described by Jerzy Neyman in his article ‘Reminiscences of a Revolutionary Period in Cosmology’. As Neumann recalled, despite initial scepticism , “Ambartsumian’s arguments and many-syded documentation made the attending scolars think, and there followed several important international developments…”Neyman concluded that “Evidence in favor of the Ambartsumian’s Hypothesis is now overhelming. My hearty congratulations to Professor V.A. Ambartsumian, the Copernican Revolutionary…!” (Problems of Physics and Evolution of the Universe, Publishing House of the Armenian Academy of Sciences, Yerevan, 1978, pp.243-250.)
A citation from the article of Nobel prize winner A.M.Kormak “Computed Tomography: some history and recent developments” (Proc. Of Symposia in Applied Mathematics, Vol 29, p35, 1985):
“… Radon’ s problem in a three dimensional velocity space…
… Ambartsumian gave the solution in two and three dimensions in the same form as Radon. Furthermore, he took groups of stars of three different spectral types, with four to five hundred stars in each group, and he used his theoretical results to deduce their actual velocity distributions from the distributions of their radial velocities….
… This is the first numerical inversion of the Radon transform and it gives the lie to the often made statement that computed tomography would be impossible without computers. Details for the calculation are given in Ambartsumian’ s paper, and they suggest that even in 1936 computed tomography might have been able to make significant contributions to, say, the diagnosis of tumors in the head….
… it seems to me quite possible that Ambartsumian’ s numerical methods might have made significant contributions to that part of medicine had they been applied in 1936….”
Amabartsumian combined his work in science with lecturing and other pedagogic activity. He is the author of the first in the USSR manual “Theoretical astrophysics” (1939) and a co-author of the course “Theoretical astrophysics” (1952), translated into many languages. Since 1931 he lectured in Lenigrad University. In 1937 Ambartsumian founded in LU the first in the USSR Faculty of Astrophysics, which he headed till 1947. In 1939-1941 Ambartsumian hold the positions of the Director of the LU Observatory and the pro-rector of LU for science. In 1941-1943 he was the Director of the Elabuga branch of the LU. In 1944 Ambartsumian founded a faculty of Astrophysics in Yerevan University.
Ambartsumian founded scientific schools in Leningrad and Byurakan that had influenced many branches of astronomy. V.A. Ambartsumian immensely contributed into science popularization by publishing booklets and articles on different problems of astrophysics.
Ambartsumian was a remarkable science organizer in Armenia, Russia and on the international level. He was the founder and the director of Byurakan Observatory, the vice-psident and then the psident of Armenian Academy of Science, member of psidium of Academy of Science of the USSR, the vice-psident (1948-1955) and the psident (1958-1961 of the Astronomical Society and twice was elected as the psident of the International Council of the Scientific Unions(1966-1972).
In 1940 Ambartsumian became a member of the Communist Party of the USSR. In 1947 was elected to the Supme Soviet of Armenian USSR. Since 1948 till 1989 Ambartsumian as a member of the Central Committee of the Armenian Communist Party. In fact Ambartsumian personifies the statepolicy of promotion of Science in the Sovjet Republic of Armenia that included considerable capital invesments and repatriation of scientists. He was a permanent delegate from Armenia to the USSR Supme Soviet between 1950-1990, was a delegate of 19th,22d & 25th Congresses of the Communist party of the USSR , in 1989 was elected to the USSR Congress of the Peoples Delegates.
V.A.Ambartsumian was awarded two Stalins Awards, Russian Federation State Award and M.V.Lomonosov Gold Medal of Academy of Science of the USSR. V.A.Ambartsumian was twice nominated the title of a Hero of Social Labor, received many medals and orders.
V.A.Ambartsumian was elected as a honoree or international member of the Academies of Science of Austria, Belgium, Bulgaria, Democratic Republic of Germany, Georgia, Denmark, Italy, London Royal Society, Netherland, the USA, France, Sweden, American Academy of Science and Art in Boston, New York Academy of Science, German Academy of Sciece (“Leopoldina”) in Halle (DRG), Royal Astronomical Societies of England and Canada, American Astronomical Society, Philosophical Society of Cambridge, as a honoree doctor the Universities of Liege, Australian National, La-Plata, Paris and Copernicus in Torun.
V.A.Amabrtsumian was awarded Gold Medals of the Pacific Ocean and British Royal Astronomical Societies, Gold Medal of Slovak Academy of Science, Jansens Medal of the French Astonomical Society, Helmgolz Medal of German Academy of Science in Berlin.
A minor planet discovered by T.M.Smirnova on May 14th 1972 in Crimea Observatory was named after Ambartsumian (1905 Ambartumyan).
Ambartsumian’ s view on astronomy of XX century