L.V. Mirzoyan. A Short Review on V.A. Ambartsumian’s Life and Activity

Chronological list of V.A. Ambartsumian's dates of life

Academician Victor Amazasp Ambartsumian is one of the most outstanding scientists of the modern times, the greatest Soviet astrophysicist, and the founder of the theoretical astrophysics school in the USSR.

He was born on September 18, 1908 in Tiflis (Tbilisi) in the family of an Armenian writer. His father, Amazasp Asatour Ambartsumian, had early noticed the uncommon abilities and interest of the son to the exact sciences and in every possible way promoted his correct education. The father’s role was rather significant in the education of the scientist. Still since his school-years, the future scientist devoted himself to problems of astronomy and theoretical physics, and especially he took a great interest in the theory of relativity of Albert Einstein. The contemporaries well remember public lectures of still schoolboy Ambartsumian about the theory of relativity read in Yerevan, which by itself and the clearness of formulations amazed even experts with their depth.

In 1924, the sixteen-year-old Victor becomes a student of the physical-mathematical department of the Leningrad (St. Petersburg) Pedagogical Institute, and in a year, of the Leningrad University. Along with the study, he begins research work and soon publishes the first scientific paper. The works of the student’s period testified to a wide range of scientific interests of their author (theoretical and mathematical physics, astrophysics).

After the graduation of the Leningrad University in 1928 Ambartsumian enters the postgraduate studies of the well-known Pulkovo Observatory where under the supervision of the great Soviet astrophysicist Academician Aristarch Apollonovich Belopolsky he progressed in the field of astrophysics. It was the period when the appearance of the modern atomic theory created necessary preconditions for rapid development of the still very young theoretical astrophysics. And Ambartsumian became the first Soviet theorist-astrophysicist.

Soon Ambartsumian comes back to the Leningrad University, this time already as a lecturer of the Mechanical-Mathematical Department, and in 1934 he founds here the Chair of Astrophysics, the first Chair on this specialty in the Soviet Union, which he heads for many years.

In 1932, Ambartsumian’s work “On the radiative equilibrium of the planetary nebulae” was published in the journal “Monthly Notices of the Royal Astronomical Society”, which became a cornerstone of the modern theory of gaseous nebulae. A series of his research devoted to the problems of physics of gaseous nebulae began with this work. In one of the papers of this series (together with N.A. Kozyrev) he succeeded to estimate for the first time the masses of the gas envelopes thrown out by Novae. The methods developed in this work are applicable in research of gas envelopes surrounding non-stable stars, and the obtained estimates of masses of these envelopes have great value for revealing of the problem of stellar evolution.

In this initial stage of activity Ambartsumian along with theoretical research performs also serious observational works.

In 1936 Ambartsumian solves the elegant problem of definition of the distribution of spatial velocities of stars by means of the distribution of their radial velocities put forward by the well-known English scientist Arthur Eddington. The solution of this problem was obtained by the so-called method of “inverse problems”. A paper containing this solution, on presentation of Eddington himself was published in the abovementioned journal of the Royal Astronomical Society.

A large contribution to astronomy was the special physical statistics for the stellar systems developed by Ambartsumian, which led to creation of the bases of the statistical mechanics of the stellar systems.

Ambartsumian’s scientific polemic with the well-known English scientist James Jeans about the age of our stellar system, Galaxy, concerns 1935-1937. Ambartsumian showed that the age of the Galaxy is by three orders (one thousand times) less than Jeans’ estimation, which was unconditionally accepted in science, and was received by him due to wrong theoretical interpretation of the observations (the statistics of elements of orbits of double stars).

Ambartsumian’s researches of those years were worthy estimated. In 1934, he was awarded Professor’s title, in 1935 an academic degree of Doctor of physical-mathematical sciences without a defense of thesis, and in 1939 he was elected a Corresponding Member of the Academy of Sciences of the USSR. Soon a new large series of Ambartsumian’s works was devoted to the study of interstellar medium in the Galaxy. In these works, a new understanding that the phenomenon of light absorption in the Galaxy is caused by the presence of numerous dust nebulae in interstellar space, absorbing clouds, was put forward and proved. On the basis of this understanding about cloudy, clumpy structure of the interstellar absorbing medium, the theory of fluctuations was developed, which played an important role in the study of the properties of interstellar absorbing clouds and put the basis of a new direction in astronomy.

The Great Patriotic War (World War II) did not stop Ambartsumian’s scientific and organizing activity. In 1941, at the beginning of the war, being the pro-rector of the Leningrad University he is appointed the Head of the research branch in Elabuga town (Tatar Autonomic Republic) where research laboratories of the University were evacuated. During the heavy war days here, under his supervision, important researches of defense and economic significance were carried out. The scientist successfully combined the leadership of the Branch with research work devoted to the problem of multiple light scattering in the opaque medium. The original theory of light scattering developed by him in these years was a large contribution to science, and the new principle put forward during the solution of this classical problem, which has received the name of “principle of invariance”, until now has important applications in physics, astrophysics, radio physics, geophysics, and in other fields of science as well.

In 1943, the Academy of Sciences of the Armenian Soviet Socialist Republic was founded, and V. Ambartsumian was one of the founders. He was elected the Vice-President. On this occasion he moves to a permanent residence to Yerevan and also becomes the director of the Yerevan Astronomical Observatory of the Academy of Sciences. The absence of large telescopes and location in the city centre extremely adversely affected the development of the astrophysical researches in the Yerevan Observatory. A question of building a new astrophysical observatory far from the city rose.

After the choice of a suitable place, in 1946, in Ashtarak region, on the southern slope of mount Aragatz and near the historical village Byurakan, the building of the Byurakan Astrophysical Observatory of the Armenian Academy of Sciences began. Along with the Observatory building in Byurakan a small group of Ambartsumian’s students, by means of very modest telescopes, actually in open-air, begins the first observations aimed at studying the structure of the Galaxy.

From now on, Ambartsumian’s name is forever associated with the activity of the Byurakan Astrophysical Observatory, which under his leadership grew in one of the recognized centres of the astronomical thought.

The theoretical analysis and the generalization of the rich observational material on stars and stellar systems of our Galaxy, stored in various observatories of the world begun by Ambartsumian still in 1930s at the Leningrad University, in 1947 were marked by the discovery of stellar systems of a new type, named “stellar associations”. The discovery of stellar associations, by the importance of conclusions following from the fact of their existence, is one of the fundamental discoveries in science of the last decades. The subsequent research of the scientist and his students were devoted to the studies of stellar associations and development of the theory of stellar associations on the basis of -various observational data on these systems obtained after their discovery.

In these researches, for the first time in science it was established that the star-formation process in the Galaxy proceeds now in stellar associations, the centres of star formation in the Galaxy, important features of kinematics and physics of the young stars forming the modern stellar associations were revealed. The results of investigation of the unusual radiation, the so-called continuous emission observed in the spectra of Ò Tauri type young stars and related non-stable objects are of a special interest. Integrally connected with physical study of stellar associations, these results have led to important conclusions concerning the nature of sources of stellar energy.

On the basis of theoretical analysis of the results of study of stellar associations, Ambartsumian developed a new hypothesis on proto-stellar matter, having a basic significance. Unlike the classical hypothesis absolutely dominating in science, according to which stars are formed in the result of condensation of the diffuse matter, the new hypothesis starts from the understanding on the existence of massive bodies, protostars, yet of unknown nature, of which stars in associations are formed as a result of their disintegration. The observational data on stellar associations give basis to admit that these protostars should possess a very high density of matter. In connection with the hypothesis of dense protostars, Ambartsumian (together with G.S. Sahakian) among a number of researches developed the theory of possible superdense configurations of the matter, baryon stars possessing a density of matter, exceeding the density of the atomic nuclei.

A big and very important series of Ambartsumian’s researches started after the discovery of radio galaxies is devoted to the questions of evolution of galaxies, huge stellar systems similar to our Galaxy. In these researches essentially new results having paramount scientific value have been received. In particular, it is necessary to note the new idea on the activity of the galactic nuclei (the central condensations), which play a decisive role in the origin and evolution of galaxies and their systems.

Due to these researches, the problem of studying of the non-stable phenomena at enormous scales observed in galaxies became the central problem of the extragalactic astronomy.

Ambartsumian’s and his students’ important researches on the discovery and investigation of the blue outbursts from the nuclei of giant galaxies, systems of galaxies of new type, the so-called compact groups of compact galaxies, etc. are related to this series, too.

In 1968 Ambartsumian offered a statistical method for estimation of the full number of flare stars in an individual stellar system on the basis of data on not numerous known stars of this type. An application of this method to the relatively young Pleiades cluster, where at that time only 60 flare stars were known, led to an unexpected result. It appeared that there should be a considerable number of flare stars in the Pleiades. It gave basis to draw an essentially important conclusion that flare stars represent an evolutionary stage, one of initial stages of the stellar evolution.

Ambartsumian’s this conclusion stimulated extensive observations of flare stars in star clusters and associations in a number of observatories, particularly in Byurakan. The obtained results, including the discovery and studies of hundreds of new flare stars in young clusters and associations have a great significance for problems of physics and evolution of stars in general.

In 1978 Ambartsumian obtained an original solution of the inverse problem on a conclusion of distribution of average frequencies of flares in the given stellar system on the basis of chronology of discovery (first flares) and confirmation (second flares) of the flare stars.

It is necessary to note, at last, that during the last years Ambartsumian works much over the theoretical interpretation of observation of the star-formation regions in our Galaxy, covering a wide range of wavelengths. He showed that these observations allow strong reasons to accept that the diffuse nebulae of our Galaxy arose completely or partly from the matter, which was thrown out by young stars.

The scientist’s contribution to the preparation of young specialists in astronomy is invaluable. Since 1931, he gives lectures at the Leningrad University. Here for the first time in our country he developed and introduced a university course of theoretical astrophysics. More than 10 years managing the Astrophysics Chair, and in 1939-41 being also the director of the Astronomical Observatory, he creates a strong school of theorists-astrophysicists, which became one of the leaders in the world. Still working at the Leningrad University, Ambartsumian maintained close connections with the Yerevan University where in different years gave courses on astrophysics, theory of relativity, integral equations, etc., supervised the post-graduate students’ work, and was the supervisor of the Astronomical Observatory.

After moving to Yerevan in 1944, Ambartsumian manages the founded by him Chair of Astrophysics. Since 1946, at the Yerevan University under his initiative the specialization in astrophysics was introduced thanks to what now the scientific personnel of the Byurakan Astrophysical Observatory consists basically of the former students of the Yerevan University, Ambartsumian’s students or the students of his students.

At the Leningrad and Yerevan Universities and in the Byurakan Astrophysical Observatory under Ambartsumian’s supervision dozens of young experts not only from Armenia, but also from different republics of our country, as well as from the socialist countries defended their Candidate and Doctoral theses. His direct students nowadays work in many large observatories and universities. Among them, there are also scientists widely known outside of our country.

Ambartsumian is the best adviser not only for his students and fellows, but also for the experienced scientists. Here is what the known Soviet astrophysicist, the director of the Crimean Astrophysical Observatory of the USSR Academy of Sciences, academician Andrey Borisovich Severny writes thereupon: “In difficult minutes of the scientific life when I had doubts in correctness of the chosen way..., I many times had to address with letters to Victor Amazaspovich and get from him either support for new undertakings, or a kind, helpful advice to follow another way”.

Ambartsumian is the author of the first textbook “Theoretical Astrophysics” in Russian (1939) by means of which several generations of young astronomers in our country were educated. In 1952, prepared under his edition and with his participation (together with known Soviet astrophysicists E.R. Mustel, V.V. Sobolev, and A.B. Severnyi), a new textbook on theoretical astrophysics was published, which then was translated and printed in English, German, and Chinese.

The book “Problems of Modern Cosmogony”, prepared under Ambartsumian’s supervision, containing a detailed statement of questions of the origin and evolution of heavenly bodies from the point of view of new ideas on this problem, was translated in German and French and several times was re-published.

Ambartsumian’s scientific and pedagogical activity is inseparably linked with organizing and public work. In the first years of his work he was the scientific secretary of the Pulkovo Observatory. At the Leningrad University, he headed the Astrophysics Chair, later simultaneously was the pro-rector on scientific work and the director of the Astronomical Observatory. In 1944-46, he was the Chairman of the Astronomical Commission and since 1952 within 12 years headed the Commission on Cosmogony in the Academy of Sciences of the USSR. Since 1955 Ambartsumian is a member of the Presidium of the Academy of Sciences of the USSR and the Council on coordination of works of the Academies of Sciences of the Union Republics, and since 1977 he was the Chairman of the Joint Scientific Council on Astronomy of the USSR Academy of Sciences. Especially it is necessary to note Ambartsumian’s fruitful activity on the positions of the President of the Academy of Sciences of the Armenian Soviet Socialist Republic (since 1947) and the Director of the Byurakan Astrophysical Observatory.

Ambartsumian played an outstanding role in the development of physical and mathematical sciences in Armenia. The republic, where practically there were no serious works in this important area of science, nowadays, thanks to regular and purposeful work of the Academy of Sciences and personally its president, is now widely known far outside the Soviet Union for the original researches in astrophysics and physics, mathematics and mechanics. By the way, great scientific successes were reached in narrow branches of these sciences, which were chosen according to the human and material possibilities of the Armenian Academy of Sciences, which provided the efficiency of the investigations.

The work on rapid rising of the level of research works in natural and technical sciences was not less successful. Directions connected with radio physics, electronics, and automatics were established and now fruitfully develop.

The progress in science in our Republic in turn stimulated the creation of industrial enterprises of new directions, development of existing industries, and considerable extension of productive forces. Branches of the advanced research-and-production associations were organized in many cities and other settlements of Armenia.

A special mention is deserved by Ambartsumian’s considerable contribution to the organization and development of the Yerevan Institute of Mathematical Machines and on this basis the creation of the industry of mathematical machines in the Republic.

Under the supervision of Ambartsumian the Academy of Sciences of Armenia reached also great successes in research of minerals, their extraction and development, in power and technology, in studying of the historical past and spiritual culture of the Armenian people.

Ambartsumian’s contribution to the development of astrophysics is invaluable. The permanent supervisor of studies of the Byurakan Astrophysical Observatory from the day of its foundation he created in Armenia a new school of astrophysics consisting exclusively from his students. In rather short time this school reached serious scientific successes, for what it deserved recognition in the scientific world. Merits of the Byurakan Astrophysical Observatory were highly appreciated. In 1967, for outstanding achievements in development of astrophysics and preparation of highly qualified scientific personnel among the number of leading Soviet research institutions, the Byurakan Observatory was awarded the highest government award, Lenin’s Order (for the moment, the only one among the astronomical institutions of the Soviet Union).

Recognition of the high level of development of astrophysics in Armenia is the decision of the Presidium of the USSR Academy of Sciences about the publication of a new all-Union journal “Astrofizika” in Yerevan since 1965. Ambartsumian was appointed the Editor-in-chief of the magazine, and along with leading Soviet astrophysicists, including Armenian scientists Ambartsumian’s students entered the editorial board. Now not only Soviet, but also foreign authors publish their papers in it, and the journal, since its first issue, is translated into English and published in the USA (as “Astrophysics”). Considering the increased inquiries of astrophysics in our country, since 1984 the volume of the journal is twice increased.

For long years (1947-1956) Ambartsumian supervised over the Publishing Council of the Academy of Sciences of Armenia, he was the Responsible Editor-in-chief of the “Reports” of the Academy (1944-1959) and a member of the editorial board of the “Astronomical journal” (1944-1979) of the USSR Academy of Sciences (Soviet “Astronomy Reports”). He is the Editor-in-chief of the “Communications of the Byurakan Observatory”, member of the editorial board of the “Reports” of the Academy of Sciences of the USSR and the international journal “Vistas in Astronomy” (“Astronomy Prospects”, England).

The first encyclopedia in Armenian, “The Armenian Soviet Encyclopedia” has been created under Ambartsumian’s supervision.

Many forces Ambartsumian gives to the work on distribution of scientific and political knowledge, propagation of achievements of the domestic science and technology in people. From the day of its foundation, he is the chairman of the “Knowledge” society of the Armenian Soviet Socialist Republic. His public lectures in Yerevan, in regions of the Republic, and also in Moscow and Leningrad, papers and interviews in all-Union and Republican magazines and newspapers, by radio and TV attract populous audiences and serve this noble work.

Especially it is necessary to mention his public lectures and conversations abroad for the Armenian Diaspora communities, which promote a strengthening of relations of foreign Armenians with their native land revived from ruins, the Soviet Armenia.

Ambartsumian’s scientific-organizing talent was excellently revealed in the field of international cooperation.

In 1948-55, Ambartsumian was the Vice-President, and in 1961-64, the President of the International Astronomical Union (IAU). On these honorable positions he conducted a big supervising work on the organization of fruitful cooperation of scientists of various countries for the decision of the most crucial problems of astronomy. His work in IAU played an important role both for raising the authority and strengthening the influence of the Soviet astronomy in this international organization.

Ambartsumian’s election (1968) as the President of the International Council of the Scientific Unions (ICSU), uniting 15 international scientific unions and academies of sciences of 60 countries, was a significant event in his life and in the history of the Soviet science in general. It was the first case when on the post of the President of the International Council a representative of the socialist country was elected. In 1970, Ambartsumian was re-elected as the President of ICSU that was an unprecedented case in the history of this Council.

Ambartsumian’s election was a worthy estimation of the scientist’s scientific merits in the world science and the largest successes of that science to which he devoted his entire creative searches.

Ambartsumian’s four-year activity on the post of the President of ICSU considerably promoted the international scientific cooperation in the decision of a number of problems, having vital importance for the whole mankind, and served for the growth of the international authority of our domestic science. Ambartsumian all the power of his talent and creative energy undividedly devoted to the progress of the spiritual and material life of his native people, the concern of development of the domestic science, aiming to see it in the forefront of the world science. Often he did it to the damage of the personal scientific work. He did it consciously, without regret, considering, that “big business demands big victims”. And this big business, the steady development of the domestic science, progress of science, culture and economy of our country, our people, was always in the centre of his attention.

The scientist takes an active participation in the public life of our country.

Since 1950, Ambartsumian was elected deputy of the USSR Supreme Soviet of all convocations, member of the Central Committee of the Communist party of Armenia, was delegate of the XIX, XX, XXII, XXIII, XXIV, XXV, and XXVI Congresses of the CPSU.

For long years he was a member of the Committee on Lenin and State awards of the USSR on Science and Technology. After the establishment of the State awards of the Armenian Soviet Socialist Republic in 1970, Ambartsumian was the chairman of the Committee on these awards.

Many years Ambartsumian supervised over the Armenian Republican Committee of Defenders of Peace, participated in works of some all-Union and international congresses in protection of Peace.

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The short review of Ambartsumian’s life and activity will be incomplete if not to tell, at least in brief, about an important streak of his character appearing in all his actions. Ambartsumian is a true patriot of his native land, the Soviet Armenia and all the Soviet Union. Simultaneously, he is a convinced internationalist. Both these feelings are indissolubly and logically connected in him.

Being born in Tiflis, in a city where representatives of almost all nationalities occupying Transcaucasia lived and worked: Georgians and Armenians, Russian and Azerbaijanians, representatives of many national minorities, Ambartsumian, since the early childhood was brought up in the spirit of internationalism, respect to cultural values of other people. In this, along with the school (at Russian school where Armenians studied in the majority, at high level there was teaching of the Armenian language and the literature), the family where the spirit of humanism and internationalism reigned, played a decisive role.

Ambartsumian’s this character trait obtained a further development in his study at the Leningrad University where he communicated with representatives of the advanced Russian science and was educated on its best traditions.

On the other hand, stories of the seniors, books of the Armenian classics and contemporaries, with many of which he had the luck to meet to at his father, one of the outstanding representatives of the Armenian intellectuals of that time, since his childhood imparted to him love to the ancient and rich culture of the native people, its thousand-year history of struggle for self-preservation, material and spiritual development.

A deep trace in his consciousness was left by the stories of seniors about the historical events of the last centuries, when the most part of Armenia was under a yoke of Ottoman Empire. During this period Armenian people underwent continuous persecutions (Ambartsumians’ generation is descendants of refugees from the Western Armenia, moved to area of Sevan, East Armenia, after its attachment to Russia in 1828) and periodic butchery.

Ambartsumian’s early childhood coincided with this, the heaviest for the Armenian people, period. He read much and heard about terrible crimes of governors of Turkey. He himself witnessed suffering of refugees, basically women, children and old men from east areas of the Western Armenia bordering with the Eastern Armenia being a part of Russia.

The Great October revolution, disinterested aid of Russian people brought liberation to his native people and helped the creation of independent Soviet Armenia on a small east part of the historical Armenia.

Ambartsumian meant this help when many years later noticed that “the Armenian people are obliged Russia not only for the rescue from the yataghan (Turkish sword) of eastern despotisms, but also the creation of conditions for their consolidation”, the beginning of which was in 1828, joining of east parts of Armenia to Russia. Ambartsumian is the apostle of friendship and cooperation between the people. Distinctly understanding that in this business special responsibility is carried by scientists, he always consistently conducts a policy of scientific and cultural cooperation between scientists of various countries and peoples.

In particular, as it has been noted above, the scientist truly served to the noble concern of organization and realization of the international scientific cooperation, strengthening of friendship between the peoples, work for peace all over the world on the posts of the Vice-President (1948-55), the President (1961-64) of the International Astronomical Union (IAU), and the President (1968-72) of the International Council of Scientific Unions.

Especially Ambartsumian values the friendship of the peoples of our immense Motherland. In particular, in the foreword to the collection of papers “From the Centennial Friendship”, devoted to the results of researches on study of the individual stages of political, economic and cultural interaction of Russia, Ukraine, Georgia, and Armenia since XVII century up to now, the scientist characterized the friendship of Russian and Armenian peoples as follows: “When you get acquainted with the history of mutual relations of Russian and Armenian peoples, you see that it is one of the most beautiful and instructive Chapters in the history of mutual relations among the peoples of our planet. And it is especially interesting, as it is a question of two peoples of which one belongs to the number of the greatest on its importance and power of nations of the world, and the other, being numerically small people, for the long periods completely lost its independence”.

More than 30 years of actual scientific cooperation and warm friendly relations already exist between Ambartsumian’s alma-mater, the Leningrad University, and the Byurakan Astrophysical Observatory. Already for many years, obvious evidence is the creation and fruitful work of the Astrophysical Observational Station of the Leningrad University in Byurakan, as well as the strong creative contacts between the two establishments for astrophysics.

An example of fruitful scientific cooperation is the creative contacts between the Academies of Sciences of Armenia and Georgia.

A stimulus for the conclusion of contract between the Academies of Sciences of two sister republics, was the scientific cooperation between the Abastumani Astrophysical Observatory of the Academy of Sciences of Georgia and the Byurakan Astrophysical Observatory of the Academy of Sciences of Armenia, begun at the period of the foundation of the latter. The contract has been signed more than ten years ago by the initiators of this undertaking, presidents of the Academies of Sciences N.I. Muskhelishvili and V.A. Ambartsumian. The past years proved the vitality of this contract, and its successful realization plays an important role in development of many areas of science in the two republics and promotes strengthening of friendship between our peoples.

In a number of fields of sciences, the Armenian Academy of Sciences fruitfully co-operates with the institutions of Academies of Sciences of the USSR, the Ukrainian Soviet Socialist Republic, the Belarus Soviet Socialist Republic, the Azerbaijan Soviet Socialist Republic, etc.

There are representatives of various nations among Ambartsumian’s direct students: Armenians, Russians, Georgians, Ukrainians, Azerbaijanians, Hungarians, Bulgarians, etc.

Scientific cooperation in various areas of astronomy; optical astronomy, radio astronomy, space astronomy, etc., in the Soviet Union co-ordinates the Joint Scientific Council on Astronomy (JSCA) of the Academy of Sciences of the USSR, headed by Ambartsumian.

The Academy of Sciences of the Armenian Soviet Socialist Republic also actively co-operates with academies of sciences of the socialist countries. There exists, for example, a direct contract on scientific cooperation between Academies of Sciences of Hungary and Armenia, which includes many actual problems in various areas of science and is successfully carried out already more than 10 years.

Scientific communications with Academies of Sciences of the German Democratic Republic (GDR) and Bulgaria are carried out in frame of the contract signed between the USSR Academy of Sciences and academies of sciences of these countries.

This year, it is 10 years of scientific cooperation on the problem “Physics and Evolution of Stars” of academies of sciences of the socialist countries (Bulgaria, Hungary, GDR, Poland, Romania, USSR, and Czechoslovakia) in which the Byurakan Astrophysical Observatory takes an active participation, too.

On Ambartsumian’s initiative, important scientific works on studying of non-stationary stars and galaxies were carried out by fellows of the Byurakan Astrophysical Observatory together with scientists of some capitalist countries (England, Holland, India, Italy, Mexico, USA, France, etc.).

The international scientific cooperation, the distribution of new scientific ideas developed in Byurakan, were much promoted by Ambartsumian’s numerous trips, conversations and performances in various countries.

The scientist’s versatile scientific, scientific-organizing, pedagogical and public work was worthy estimated. He was twice awarded the title of Hero of Socialist Work, he is holder of five Lenin Orders, an Order of October Revolution, two Orders of Labour Red Banner, other orders and medals of the USSR. In 1971, Ambartsumian was awarded the highest award of the USSR Academy of Sciences, the Lomonosov gold medal, and in 1970, the Vavilov medal. His researches twice (in 1946 and 1950) were noted by the USSR State awards. Since 1953, the scientist is a full member of the USSR Academy of Sciences, was elected an honorary member of Academies of Sciences of the Georgian Soviet Socialist Republic and the Azerbaijan Soviet Socialist Republic. He is an Honoured Scientist of the Armenian Soviet Socialist Republic and the Georgian Soviet Socialist Republic.

Ambartsumian’s scientific merits have received wide recognition and are highly appreciated also abroad. He was elected an honorary and foreign member of academies of sciences of many countries: National Academy of Sciences of the USA, the Royal Society (Academy of Sciences) of England, Academy of Sciences of Austria, Athens (Greece), Belgian Royal, Bulgaria, GDR, Holland, Denmark, India, Italy, Cordoba (Argentina), Swedish Royal, Czechoslovakia, and France. He is elected also an honorary member of the Academy of Sciences of New York, the American Academy of Arts and Sciences (Boston), the Academy of Naturalists “Leopoldina” (Halle, GDR), Corresponding Member of the International Academy of Astronautics, honorary member of the Cambridge (England) Philosophical Society, Royal Astronomical Societies of England and Canada, the American Astronomical Society.

Ambartsumian was given a title of honorary doctor of sciences (“honoris causa”) of universities of Canberra (Australia), La Plata (Argentina), Liege (Belgium), Prague (Czechoslovakia), Sorbonne (Paris, France), and Torun (Poland).

The scientist’s scientific researches were noted by Gold medals after Helmholtz (Academy of Sciences of GDR), Academy of Sciences of Czechoslovakia, after Kotenius (Academy “Leopoldina”, GDR), Slovak Academy of Sciences, after Katarina Bruce (the Astronomical Society of the Pacific, USA), the Jansen medal of the French Astronomical Society and Sarmiento medal of the Cordoba Academy of Sciences (Argentina).

At last, Ambartsumian was awarded government awards of Bulgaria, Hungary, Poland, and Czechoslovakia.

The highest estimation of the scientist’s merits, however, are the deep respect and sincere love of our people to their remarkable son, people surrounding him almost every day who become eyewitnesses of various displays of these merits.