Background

Sergey Nikolaevich Blazhko was born on November 17, 1870, in Khotimsk, Mogilevskaya province, the son of a merchant who had risen from the enserfed peasantry.

Education

Blazhko graduated from the Smolensk Gymnasium in 1888 and from the Physics and Mathematics Faculty of Moscow University in 1892.

Career

From 1894 to 1915 Blazhko was an assistant at Moscow Observatory and from 1915 to 1918, an astronomer-observer there. In 1918 he became a 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 astrometry from 1937 to 1953.

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 Shapley, who, independently of Blazhko, developed methods for studying eclipsing binary stars, not only of the Algol type.

In 1919 Blazhko proposed an original photographic method for discovering minor planets - the method of triple exposure 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.

Achievements

• Blazhko's major academic achievement was in his dedicated study of eclipsing binary stars of the Algol type. He became the first to give a general method for determining the elements of the orbits of eclipsing binaries in 1911. 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.
  
  Another Blazhko's achievement was in the development of an original photographic method for discovering minor planets - the method of triple exposure on one plate with intervals between exposures and with a shift in the declination of the telescope during the intervals. He also devised a number of original instruments, such as 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.
  
  Blazhko's contribution to the field of astronomical science was greatly recognized and in 1929 he was elected an associate member of the Academy of Sciences of the Soviet Union. He received the title Honored Scientist of the RSFSR 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. Sergey Nikolaevich Blazhko was also awarded the USSR State Prize (1952). The crater Blazhko on the Moon is named after him.

Works

• book

  • Course of spherical astronomy 1954
  • Kurs prakticheskoi astronomii 1950

Views

Blazhko’s primary sphere of scientific activity was the study of variable stars.

Membership

In 1929 Blazhko became an associate member of the Academy of Sciences of the Soviet Union.

Connections

In 1917 Sergey Nikolaevich Blazhko married Maria Ivanovna Ushina, a teacher.

Wife:

Maria Ivanovna Ushina

colleague:

Pavel Karlovich Shternberg

Pavel Karlovich Shternberg (April 2, 1865 – February 1, 1920, both dates New Style) was a Russian astronomer and revolutionary, who contributed to the abolition of the government by Alexander Kerensky. He was friends with two notable figures, Vladimir Lenin and Leon Trotsky. His significant contributions include the discovery of the planetary perturbations, the measurement of the latitude of the Moscow Astronomical Observatory, and application of the photography to astronomy. The primary subject of his photography was capturing double stars.

References

• The Biographical Encyclopedia of Astronomers
  2009
• Dictionary of scientific biography
  1981