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Shayn, Grigory Abramovich

SHAYN, GRIGORY ABRAMOVICH

(b. Odessa, Russia, 19 April 1892; d. Abramtsevo, near Moscow, U.S.S.R., 4 August 1965)

astrophysicist.

The son of a joiner, Shayn completed only elementary school; but in 1911 he passed with distinction the examinations for the graduation certificate as an extramural student. He became interested in astronomy at the age of ten, and at fourteen or fifteen he seriously observed meteors with binoculars; in 1910 his first scientific work, “Vychislenie radianta Perseid” (“A Calculation of the Radiant of the Perseids”), was published in Izvestiya Russkogo astronomicheskogo obshchestva (16 , no. 5, 194–197).

In 1912 Shayn entered the Faculty of Physics and Mathematics at Yurev (Dorpat) University. After serving in the army from 1914 to 1917, he completed his university education in 1919 at Perm, to which the university had been evacuated, and began his teaching career. The following year he passed the examinations for the master’s degree and became an assistant in the department of astronomy at Tomsk University. In 1921 he transferred to Pulkovo and devoted himself completely to scientific work.

In 1925 Shayn and his wife, Pelageya Fedorovna Sannikova, moved to the Simeiz section of the Pulkovo observatory, where Shayn supervised the insallation of a 102-centimeter reflector, which had been ordered before the war from the British firm of Grubb. In January 1926 the first spectrogram was obtained with it. Shayn worked with this instrument until World war II. In 1935 he was awarded the doctorate in physical and mathematical sciences. Two years later he was elected foreign member of the Royal Astronomical Society, and in 1939 he became an academician of the Soviet Academy of Sciences.

During World War II part of the staff of the Simeiz observatory was evacuated to the Abastumani astrophysical observatory in Georgia, and there Shayn continued to study spectrograms evacuated from Simeiz. After the war Shayn participated in restoring the destroyed Simeiz observatory and in building a large modern astrophysical observatory in the mountain of the central Crimea. In 1945 he was named director of the Crimean Astrophysical Observatory of the Soviet Academy of Sciences. Seven years later, having asked, for reasons of health, to be relieved of his responsibilities as director, Shayn was named head of the section on the physics of nebulae and interstellar mediums. During the following four years he carried out important investigations of nebulae and galactic magnetic fields.

In the 1920’s Shayn became interested in the evolution of stars and turned to double stars, correctly asserting that their components must be of the same age. He compared the most reliable data obtained from the literature on the components of double stars, in order to construct a “spectrumluminosity” (Hertzsprung-Russell) diagram. Shayn studied the evolution of doubles, the changes in the proportions of the masses of the components, and the mass-luminosity and spectrum-luminosity relationships. He drew the important conclusion, later fully confirmed, that the evolution of the larger component must be more rapid than that of the smaller.

At the same time as O. Struve, and in partial collaboration with him by means of correspondence, Shayn discovered the rapid rotation of a number of stars of early spectral classes by analyzing the form of the spectral lines. Theoretically considering the forms of spectral lines of rotating and non-rotating stars, he provided a method of determining the velocity of rotation. With V. A. Albitsky, Shayn obtained precise determination of the radial velocity of about 800 stars, discovered several dozen spectroscopic binaries, and computed the elements of the orbits of many of them.

Spectrophotometry was a natural continuation of Shayn’s study of spectroscopic binaries. His aim was to investigate the behavior of the absorption lines and bands and their influence on the color of the stars, their apparent bolometric magnitudes and other properties, and the relation of the normal color to luminosity. Research on the spectra of the long-period variables was associated with the elucidation of all the peculiarities of the spectrumluminosity and period-luminosity relationships. A number of Shayn’s spectrophotometric investigations dealt with planetary nebulae, the integral spectrum of the Milky Way clouds, and the spectrum of the rings of Saturn. His observations of the total solar eclipse of 1936 provided material for the study of the physics of the solar corona.

At Abastumani, Shayn used spectrograms from Simeiz to offer an original interpretation of the coexistence of emission lines and lines of absorption (high-and low-temperature spectra) in the spectra of long-period variables such as Mira Ceti. A paradox was removed by the hypothesis that the physical obscuration of the source of high-temperature radiation was provided by the extended atmosphere of such a star. Shayn indicated the possible similarity of the turbulent phenomena of solar activity (chromospheric flares and similar processes) to phenomena that cause the outward motion of hot matter from a star and the appearance of emission lines in its spectrum.

Shayn conducted important research on isotopes in the atmospheres of stars. In 1940 he discovered that the isotope C13 content in several stars was very great: for the earth the proportion of C13 to C12 is approximately 1:70–1:90, for the sun it is less than 1:10, while on certain red so-called carbon stars it reaches 1:2. Besides the two known bands of the heavy molecule of cyanogen C13N14, Shayn also demonstrated the presence of many bands in the red and violet range of the spectra of these stars. American physicists were thus led to make a new experimental determination of the cross section of the capture of protons by the nuclei of C12 and C13. As a result it was unexpectedly shown that the amount of isotope C13 on earth and on the sun is abnormally small. For his work on isotopes in the atmospheres of carbon stars Shayn was awarded the State Prize in 1950.

By 1948 Shayn and his collaborator of many years, Vera F.Gaze, had developed a special method of photography based on the fact that gas nebulae radiate all their energy in certain bright emission lines. Using two meniscus cameras with objectives of 450 millimeters of high optical efficiency (1:14) and a field of about 4°, they discovered more than 150 new emission nebulae and published several catalogs of diffuse nebulae, as well the photographic Atlas diffuznykh gazovykh tumannostey (“Atlas of Diffuse Gas Nebular”;1952). Using the same method, Shayn also found emission objects in other galaxies. All these nebulae appeared to be distributed along the branches of spirals. From 1950 Shayn used a more powerful 640-millimeter camera.

In the galactic emission nebulae he noted peculiarities in the distribution of the matter in the so called peripheral nebulae, and he concluded that the nebulae expanded over the course of time. From this he formulated the important cosmogonic statement of the common formation of the Association of hot stars and nebulae. Studying the continuous spectra of certain diffuse nebulae, he showed that in accord with the hypothesis of A.Y. Kipper (Tartu), the continuous spectrum of nebulae is related not to the scattering of light by interstellar dust but to the “two-quantum jump” in hydrogen atoms. Shayn concluded that the role of the dust had been exaggerated, for its density proved to be much less than that of the gaseous medium (for example, 1/100 in the Orion nebula).

Studying the filamentary nebulae, Shayn found that in most cases the filaments were oriented parallel to the galactic equator; to explain their elongation and orientation he posited the existence in the galaxy of powerful magnetic fields. He discovered that the direction of the elongated nebulae was similar to the direction of the plane of polarization of light. This made it possible to define the borders of the branches of our galaxy more precisely and to assert the presence of an “arm” in the direction of the constellation Sagittarius. The magnetic theory explained why the gas does not disperse beyond the branches and does not fill the space between the “arms” of the spirals.

BIBLIOGRAPHY

I. Original Works. A complete bibliography of 249 titles, complied by N. B. Lavrova, is Istoriko-astronomicheskie issledovaniya, 3 (1957), 596–607. Among them are “On the Rotation of Stars,” in Monthly Noticesof the Royal Astronomical Society, 89 (1929), 222 –239, written with O. Struve; “The Absorption Continuum in the Violet Region of the Spectra of Carbon Stars,” in Astrophysical Journal, 106 (1947), 86–91, written with O. Struve; “Otnoshenie kontsentratsii isotopov C13 i C14 v atmosferakh zvezd” (“The Relative Concentration of the Isotopes C13 and C14 in the Atmosphere of Stars”), in Uspekhi fizicheskikh nauk, 43 (1951), 3–10, written with V. F. Gaze; “Certain Peculiar Structures in Interstellar Clouds,” in Gas Dynamics of Cosmic Clouds (Amsterdam. 1955), 37–38; and “On the Groups of Diffuse Emission Nebulae,” in Vistas in Astronomy, II (London, 1955), 1066–1069.

II. Secondary Literature. See “Akademik Grigory Abramovich Shayn. 1892–1956,” in Vestnik Akademii nauk SSSR (1956), no. 10, 84; “Akademik Grigory Abramovich Shayn,” in Voprosy kosmogonii, 5 (1957), 3–5; P. P. Dobronravin, “Grigory Abramovich i Pelageya Fedorovna Shayn,” in Peremennye zvezdy, 11 , no. 4 (1958), 321–324; “G. A. Shayn (1892–1956),” in Astronomicheskii zhurnal, 33 , no. 4 (1956), 465–468, with portrait; “Grigory Abramovich Shayn in Izrestivu Krymskoi astrofizicheskii obserratorii, 17 (1957), 3–10; “Grigory Abramovich Shayn (1892–1956),” in Materials k biobibliografii uchenykh SSSR, Astron, ser. (1960), no. 2, intro. by P. P. Dobronravin and bibliog raphy by O. V. Isakova; S. B. Pikel’ner, “G. A. Shayn,” in Astronomicheskii tsirkulyar. Byuro astronomicheskikh soobshchenii, Akademiya nauk SSSR, no. 172 (1956), 1–2; and “G. A. Shayn (1892–1956),” in Istoriko-astronomicheskie issledovaniya, 3 (1957), 551–607, with complete bibliography of 249 titles compiled by N. B. Lavrova, 596–607: the article “Shayn” in Bolshaya sovetskaya entsiklopedia (“Great Soviet Encyclopedia”), 2nd ed., XLVII, 499; and O. Struve, “G. A. Shain and Russian Astronomy,” in Sky and Telescope, 17 , no. 6 (1958), 272–274.

P. G. Kulikovsky

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