IMPORTANT SCIENTIFIC RESULTS OBTAINED AT BAO


The main achievements of the Armenian astronomy are connected with V.A. Ambartsumian and development of his ideas and projects in Byurakan starting with the very first years of its foundation. Ambartsumian ideas put the basis of new views on origin and evolution of cosmic objects and new approaches in observational and theoretical investigations resulting in many important discoveries during a few decades. Following Ambartsumian’s ideas, another prominent Armenian astronomer, B.E. Markarian, conducted and accomplished the famous Byurakan Surveys, the most important observational works made in the Byurakan Observatory, and several other projects were undertaken based on them. This is the first attempt to list the most important results obtained in Byurakan and/or by Byurakan astronomers in collaboration with foreign colleagues. Any comments and complements are welcome.

The most important scientific results have been selected and are listed according to criteria that they must be one of the following:

1947 Discovery of stellar associations, groups of hot (OB) giants and T Tauri stars. It was shown for the first time that the star formation process continues at all stages of the evolution of our Galaxy, including the present one and that the star formation is a permanent process (the maximum ages of stellar associations were estimated at 107 yr compared to 1010 yr of the age of the Galaxy). A conclusion was drawn that stars are formed not individually, but in groups (V.A. Ambartsumian).
V.A. Ambartsumian, Evolution of Stars and Astrophysics // Acad. Sci. ArmSSR), 39 p., Yerevan, 1948 (in Armenian).
V.A. Ambartsumian, Preliminary Data on O-Associations in the Galaxy // Doklady USSR Acad. Sci., Vol. 68, No. 1, p. 21-22, 1949 (in Russian).
1949-1951 Theoretical prediction of the phenomenon of expansion of stellar associations. Revealing the importance of the stellar associations as dynamically unstable entities. Statistics of the Trapezium Orionis type systems and a proof of disintegration of the young stellar systems based on measurements of the proper motions of stars (V.A. Ambartsumian, B.E. Markarian).
V.A. Ambartsumian, Stellar Associations // Astron. Zh., Vol. 26, No. 1, p. 3-9, 1949 (in Russian).
V.A. Ambartsumian, B.E. Markarian, Stellar Association around P Cygni // Communications of the Byurakan Observatory, No. 2, p. 3-17, 1949 (in Russian).
V.A. Ambartsumian, On the Frequency of the Orion Trapezium type Apparent Multiple Systems // DAS ArmSSR, Vol. 13, No. 4, p. 97-103, 1951 (in Russian).
V.A. Ambartsumian, On the Statistics of Trapezium type Multiple Systems // Doklady Acad. Sci. ArmSSR, Vol. 13, No. 5, p. 129-131, 1951 (in Russian).
1954 Prove of the nonthermal nature of the continuous emission observed in the spectra of non-stable stars and putting forward an idea about new possible sources of stellar energy, the hypothesis of the superdense protostellar matter (V.A. Ambartsumian).
V.A. Ambartsumian, The Phenomenon of the Continuous Emission and Sources of Stellar Energy) // Comm. BAO, No. 13, p. 1-36, 1954 (in Russian).
1956 Statistical proof that radiogalaxies could not happen due to collisions of two galaxies (V.A. Ambartsumian).
1956 The hypothesis on the activity of galactic nuclei. The various forms of activity were presented as different manifestations of the same phenomenon of activity. The evolutionary significance of the activity in the galactic nuclei was emphasized and a further hypothesis was suggested on the ejection of new galaxies from the active galactic nuclei. The hypothesis on the superdense protostellar matter was engaged to explain the observational data (V.A. Ambartsumian).
V.A. Ambartsumian, On the Nature of Radio Sources) // Proc. Fifth conf. on Problems of Cosmogony: "Radioastronomy", held on 9-12 Mar 1955. Acad. Sci. USSR), p. 413-416, Moscow, 1956 (in Russian).
V.A. Ambartsumian, On Multiple Galaxies // Izvestiya Acad. Sci. ArmSSR, Ser. Phys.-Math., Nat. and Tech. Sci., Vol. 9, No. 1, p. 23-43, 1956 (in Russian).
1957-1958 Discovery of blue outbursts and companions near elliptical galaxies supporting Ambartsumian’s hypothesis of activity of galactic nuclei (V.A. Ambartsumian, R.K. Shahbazian).
V.A. Ambartsumian, R.K. Shahbazian, Multiple Galaxies and Radiogalaxies. Report II. Blue Outbursts and Companions of Elliptical Galaxies // Doklady Acad. Sci. ArmSSR, 25, 4, p. 185-192, 1957 (in Russian).
V.A. Ambartsumian, R.K. Shahbazian, Multiple Galaxies and Radiogalaxies. Report IV. Blue Objects near the Elliptical Galaxies // Doklady Acad. Sci. ArmSSR, Vol. 26, No. 5, p. 277-279, 1958 (in Russian).
1960-1961 Theoretical studies of the hypothetical superdense degenerate protostellar matter: development of principles of the theory of baryonic stars, which allowed a detailed research of physical conditions in superdense stellar conditions in the frame enabled by the modern knowledge of physics. These researches later on allowed increasing the Chandrasekhar limit of stellar masses (V.A. Ambartsumian, in collaboration with G.S. Saakyan, Yerevan State University).
V.A. Ambartsumian, G.S. Saakyan, The Degenerate Superdense Gas of Elementary Particles // Soviet Astronomy, Vol. 4, No. 2, p. 187-201, 1960.
V.A. Ambartsumian, G.S. Saakyan, On Equilibrium Configurations of Superdense Degenerate Gas Masses // Soviet Astronomy, Vol. 5, No. 5, p. 601-610, 1962.
V.A. Ambartsumian, G.S. Saakyan, Internal Structure of Hyperon Configurations of Stellar Masses // Soviet Astronomy, Vol. 5, No. 6, p. 779-784, 1962.
1963 Discovery of superassociations in distant galaxies, large blue formations, later found to be emission-line objects and called HII regions. A proof of young age of these galaxies (V.A. Ambartsumian, S.G. Iskudarian, R.K. Shahbazyan, K.A. Sahakian).
V.A. Ambartsumian, S.G. Iskudaryan, R.K. Shahbazyan, K.A. Saakyan, Superassociations in Distant Galaxies // Comm. BAO, Vol. 33, p. 3-18, 1963 (in Russian).
1964 Application of the principle of invariance to the solutions of non-linear problems of the radiation transfer theory; solution of the problem of the reflection of monochromatic radiation from one-dimensional medium. Formulation of a new method; the principle of self-consistent optical depths for the study of non-linear scattering processes (V.A. Ambartsumian).
1965 Estimation of the frequency of supernovae in supergiant galaxies as one in 20-30 years (V.A. Ambartsumian).
V.A. Ambartsumian, Comments on the question of the frequency of supernovae // Astrophysics, Vol. 1, No. 4, p. 248, 1965.
1968 Statistical studies of the flare stars revealed their evolutionary status: a method for estimation of the total number of flare stars in a star system based on the number of the observed flares. The flare activity was shown to be the regular stage in the evolutionary path of the low luminosity and low mass late-type stars. It was proved that all the stars of the mentioned category necessarily pass through the stage of flare activity in the early phases of their evolution (V.A. Ambartsumian).
V.A. Ambartsumian, On the Statistics of Flare Objects // Proc. symp. "Stars, Nebulae, Galaxies", devoted to the 60th anniversary of academician V.A. Ambartsumian, held in Byurakan, 16-19 Sep 1968. Acad. Sci. ArmSSR, p. 283-292, Yerevan, 1969 (in Russian).
1971 Explanation of the change of brightness of FU Ori star by the expansion of its gaseous envelope. Introducing the class of Fuors (V.A. Ambartsumian).
V.A. Ambarstumian, Fuors // Astrophyiscs, Vol. 7, No. 4, p. 331-339, 1971.
1964-1970s The Byurakan classification of central regions of spiral galaxies based on the study of the central regions of more than 700 objects; revealing galaxies with star-like and split nuclei, possible AGN (V.A. Ambartsumian, A.T. Kalloghlian, H.M. Tovmassian, K.A. Sahakian, S.G. Iskudarian, E.S. Parsamian).
A.T. Kalloghlian, H.M. Tovmassian // Commun. BAO, Vol. 36, p. 31, 1964.
H.M. Tovmassian // Astrofizika, Vol. 1, p. 197, 1965.
H.M. Tovmassian // Astrofizika, Vol. 2, p. 317, 1966.
K.A. Sahakian // Astrofizika, Vol. 4, p. 41, 1968.
E.S. Parsamian // Astrofizika, Vol. 4, p. 150, 1968.
S.G. Iskudarian // Astrofizika, Vol. 4, p. 385, 1968.
1978 The original solution of the inverse problem of derivation of the distribution function of average frequencies of flares in the given stellar system on the basis of the chronology of discovery (first flares) and the chronology of confirmation (the temporal distributions of repeated flares) of the flare stars (V.A. Ambartsumian).
V.A. Ambartsumian, Derivation of the frequency function of stellar flares in a star cluster // English translation in: Astrophysics, Vol. 14, No. 3, p. 209-217, 1978.
1978-1979 Study of the UV spectrum of the peculiar star P Cyg; detection of largely expanded photosphere. It was shown that the acceleration of the outflow of matter from this star begins in the deep layers of its photosphere (V.A. Ambartsumian, L.V. Mirzoyan, in collaboration with T.P. Snow, USA).
V.A. Ambartsumian, L.V. Mirzoyan, T.P. Snow, P Cygni in the Far Ultraviolet // Astrofizika, Vol. 14, No. 3, p. 425-438, 1978.
V.A. Ambartsumian, L.V. Mirzoyan, T.P. Snow, Ultraviolet observations of P Cygni with Copernicus // Astrophys. J., Vol. 227, No. 1, p. 519-525, 1979.

1952 Compilation and publication of the Atlas of stellar clusters of various types (B.E. Markarian).
B.E. Markarian, Atlas of Stellar Clusters of Various Types // Publication of the Astronomical Council, Moscow, 1952 (in Russian).
1958-1966 Detailed photometric and colorimetric investigations of nearby galaxies and galaxies in the Virgo cluster for determination of the distribution of colors and hence the different stellar populations in them (B.E. Markarian, A.T. Kalloghlian, E.S. Hovhannessian, S.N. Arakelian).
1963 Selection of galaxies with anomalous spectral features for their type. Explanation of the excessive UV as non-thermal radiation. Understanding the principles for search for new active galaxies and conduction of the First Byurakan Survey (B.E. Markarian).
B.E. Markarian, On the Nature of Galaxies Having Anomalous Spectral Features for their Type // Communications of BAO, No. 34, p. 3-18, 1963 (in Russian).
1965-1980 The First Byurakan Survey (FBS), the first systematic and the largest objective prism spectroscopic survey (17,000 sq. deg.). 1500 UV-excess galaxies were revealed (Markarian galaxies). Many new AGN and Starburst galaxies were found.(B.E. Markarian, V.A. Lipovetski, J.A. Stepanian).
B.E. Markarian, Galaxies with an Ultraviolet Continuum // Astrophysics, Vol. 3, p. 55-68, 1967.
B.E. Markarian, V.A. Lipovetski, J.A. Stepanian, L.K. Erastova, A.I. Shapovalova, Catalogue of Markarian Galaxies // Communications of SAO, Vol. 62, p. 1-117, 1989. VizieR On-line Data Catalog: VII/172.
1978-1991 The Second Byurakan Survey (SBS), a deeper and higher resolution large area (965 sq. deg.) sky survey for UV-excess and emission-line galaxies and QSOs, and blue stars. Objects filling the gap between Local Universe AGNs and distant QSOs were revealed (B.E. Markarian, J.A. Stepanian, L.K. Erastova, V.A. Lipovetski, V.H. Chavushian, et al.).
B.E. Markarian, V.A. Lipovetski, J.A. Stepanian, The Second Byurakan Spectral Sky Survey. I. Quasistellar and Seyfert Objects // Astrophysics, Vol. 19, p. 29-43, 1983.
J.A. Stepanian, The Second Byurakan Survey. General Catalogue // Revista Mexicana de Astronomia y Astrofisica, Vol. 41, p. 155-368, 2005.
1980-1988 Spectroscopic studies of the First Byurakan Survey galaxies – galaxies with UV continuum. Discovery of many new Seyfert galaxies and other AGN (B.E. Markarian, V.A. Lipovetski, J.A. Stepanian, L.K. Erastova).
B.E. Markarian, L.K. Erastova, J.A. Stepanian, V.A. Lipovetski, A.I. Shapovalova, Spectra of Galaxies with UV-Continuum. VII // Astrofizika, Vol. 28, p. 476-486, 1988 (and references therein).
1980-1999 Spectroscopic studies of the SBS stellar objects; discovery of hundreds of new QSOs, white dwarfs, hot subdwarfs, HBB stars, cataclysmic variables, planetary nebulae, etc (B.E. Markarian, J.A. Stepanian, V.A. Lipovetski, L.K. Erastova, V.H. Chavushian, in collaboration with astronomers from Mexico).
J.A. Stepanian, V.H. Chavushyan, L. Carrasco, H.M. Tovmassian, L.K. Erastova, Spectroscopy of Stellar-like Objects Contained in the Second Byurakan Survey. I // Publ. Astron. Soc. Pacific, Vol. 111, No. 763, p. 1099-1114, 1999 (and references therein).






















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