Blazhko, Sergei Nikolaevich

(b. Khotimsk-Mogilevskaya Province, Russia, 17 November 1870; d. Moscow, U.S.S.R., 11 February 1956)

astronomy.

The son of a merchant who had risen from the enserfed peasantry, Blazhko graduated from the Smolensk Gymnasium in 1888 and from the Physics and Mathematics Faculty of Moscow University in 1892. From 1894 to 1915 he was assistant at Moscow Observatory and from 1915 to 1918, an astronomer observer there. In 1917 he married Maria Ivanovna Ushina, a teacher. In 1918 he became professor of astronomy at Moscow university and from 1920 to 1931 was, simultaneously, director of the observatory. From 1922 to 1931 he was also director of the university’s Scientific Research Institute of Astronomy and Geodesy.

Blazhko’s pedagogic career began in 1896, when he was entrusted with conducting exercises in practical astronomy at the university. From 1900 to 1918 he taught astronomy at the Women’s Pedagogical College, and from 1909 to 1919 at the A. L. Shanyavsky People’s University; from 1910 to 1918 he was Privatdozent and from 1918 professor at Moscow University; at the latter he held the chair of astronomy from 1931 to 1937 and the chair of astronomy from 1937 to 1953. In 1929 Blazhko was elected an associate member of the Academy of Sciences of the U.S.S.R. He received the title Honored Scientist of the R.S.F.S.R. in 1934 and was twice awarded the Order of Lenin and the Order of the Red Banner of Labor. He also belonged to numerous astronomical societies, both Russian and foreign.

Blazhko’s primary sphere of scientific activity was the study of variable stars. In 1895 he began the systematic photographing of the heavens with a special “equatorial camera” built in Germany according to the design of V.K. Cerasky, director of the Moscow Observatory. He hoped, through comparison of plates taken at different times, to discover new variable stars. He also conducted visual observations of variable stars over several decades. Through these observations Blazhko discovered the periodic change of the periods and the shape of light curves of a number of short-period variable stars of the type RR Lyrae, a phenomenon that came to be called the “Blazhko effect.” In all, Blazhko investigated more than 200 variable stars, and his valuable series of observations, which covered many years, is still used.

Blazhko’s other scientific work involved photographing the sun with a photoheliograph in order to determine the period of its rotation according to the motion of its faculae (1895); obtaining spectra of two meteors in 1904 with an apparatus of his own construction; one of the first detailed investigations of meteor spectra (1907); and one of the first investigations of the spectrum of the eclipsing variable star U Cephei. Blazhko later obtained the spectrum of another meteor, and these three spectra were long among the first five known.

Blazhko devoted special attention to the study of eclipsing binary stars of the Algol type. In 1911, in his dissertation, “O zvezdakh tipa Algolya” (“On Stars of the Algol type”), he was the first to give a general method for determining the elements of the orbits of eclipsing binaries. He also provided the first analysis of the influence of darkening toward the limb of a star’s disk on the shape of the light curve. However, one must note that in 1912–1913 there appeared in the united States a series of articles by H. N. Russel and Harlow Shaply, who, independently of Blazhko, developed methods for studying eclipsing binary stars, not only of the Algol type but of other types as well (β Lyrae and W Ursae Majoris).

In 1919 Blazhko proposed an original photographic method for discovering minor planets—the method of triple exposure on one plate with intervals between exposures on one plate with intervals between exposures and with a shift in the declination of the telescope during the intervals. He devised a number of original instruments: a star spectrograph, a blink-microscope, a special magnifying glass for reading the division marks of meridian circles, and a device for eliminating the “stellar magnitude equation” from the times of transit taken with meridian instruments.

BIBLIOGRAPHY

1. Original Works. Principal works include “On the Spectra of Two Meteors,” in Astrophysical journal, 26 , no. 5 (1907), 341–348; “Über der Veränderlichensterne U Cephei,” in Astronomische Nachrichten, 181 (1909), 295–298; “Étude de I’ étoile RW Draconis à la lumière variable,” in in russkii astronomicheskii zhurnal, 1 , no. 2 (1924); Kopernik (Moscow-Leningrad, 1926); “Sur le variable XZ Cygni à période et à courbe de lumière variable,” Annales de l’ Observatoire astronomique de Moscoue, 2nd ser., 8 (1926), 23–41; Photographische Aufnahmen der kleiner Planeten auf der Universitäts-sternwarte zu Mostau,” in Astonomischhe Nachrichten, 232 (1928), 131–134; “O spektre meteora 1907 g. avgusta 12” (“On the Spectrum of the Meteror of 12 August 1907”), in Russkii astronomicheskii zhurnal, 9 , nos. 3–4 (1932), 146–162; kurs prakticheskoy astronomii (“Course of Practical Astronomy” Moscow-Leningrad, 1938; 3rd ed., 1951); “Istoria Moskovskoy astronomicheskoy observatory v svyazi s istorey prepodavania astronomy v universitete (1824–1902)” (“History of the Moscow Astronomical Observatory in Connection with the Teaching of Astronomy at the University [1824–1920]”), in Uchenye zapiski MGU, jubilee ser., no. 58 (1940), 5–106; kurs obshchey astronomy (“Course of General Astronomy” Moscow-Leningrad, 1947); and Kurs sfericheskoy astronomy(“Course of Spherical Astronomy” Moscow, 1948; 2nd ed., 1954).

II. Secondary Literature. Works on Blazhko are B.V. Kukarkin, “Sergei Nikolaevich Blazhko(Necrolog),” in Peremennye zvezdy, 11 , no. 2 (1956).63–64, with portrait; P.G. Kulikovsky, “50-letny yubiley S.N. Blazhko,” in Astronomicheskii Kalendar na 1945 god (Gorki, 1945), pp. 205–207; “Zasluzhenny deyatel nauki S. N. Blazhko K 80-letiyu so dnya rozhdenia,” in Priroda (1951), no. 8, 59–61; and “Sergei Nikolaevich Blazhko,” in Astronomicheskii kalendar na 1957 god (Moscow, 1956), pp. 275–276, with portrait; the obituary "Setgei Nikolaevich Blazhko (1870–1956. Necrology),” in Astronomicheskii zhurnal, 33, no 2 (1956), 278–280, with portrait ; and V. V. Podobed, “S. N. Blazhko,” in Astronomicheskii tsirkular, no, 168(1956), 1–2.

P.G. Kulikobvsky