Bredikhin, Fedor Aleksandrovich

(b. Nikolaev, Russia, 8 December 1831; d St. Petersburg. Russia, 14 May 1904)

astronomy.

Bredikhin was born into an old aristocratic family. His father, Aleksandr Fedorovich, served with the Black Sea fleet; his mother, Antonida Ivanovna Rogulya, was the sister of an admiral. Since all of his uncles were naval officers, it was expected that Bredikhin would join the navy, but science attracted him instead. Until 1845 he studied at home; at Solonikha, his father’s estate near Kherson; and at the Lycée Richelieu in Odessa. In 1851 he enrolled in the Physics and Mathematics Faculty of Moscow University, where he became interested in physics and, in his final year, astronomy.

After graduation in 1855 Bredikhim stayed at the university in order to prepare for a teaching career. He also worked at the Moscow observatory, which was directed by the famous “discoverer of comets,” K. G. Schweizer. In 1858–1859 Bredikhin began teaching a lecture course at the university.

He married Anna Dmitrievna Bogolovskaya in 1860; their son, Aleksandr, died tragically in 1888. Bredikhin was a man of great general learning. He knew several European languages, possessed undoubted literary ability, loved music, and played the violin.

In 1861 he published his first scientific paper, “Quelques mots sur les queues des comètes” (on the bright comet Donati of 1858, which, in addition to its primary tail, had several weaker, more distorted ones). At this time he began his series of remarkable investigations of the nature of comets, which was the major work of his life. In 1862 Bredikhin defended his mater’s thesis, O khovostakh komet (“On the Tails of Comets”), and in 1863 was designated deputy extraordinary professor in the astronomy department. He defended his doctoral dissertation, “Vozmushchenia komet, nezavisyashchie ot planetnykh prityazheny” (“Comet Perturbations Which Are Not Caused by Attractions by the Planets”) in 1865 and became an ordinary professor. In 1867–1868 Bredikhin visited Italy, where the first classification of star spectra had been developed and where, generally speaking, astrophysics was rapidly being developed. There he studied the technique of spectroscopic observation with Secchi, Tacchini, and other astrophysicists.

After Schweizer’s death in 1873, Bredikhin became director of the Moscow observatory, where his fundamental works on the study of comets were written. In 1890, following Struve’s retirement, he was elected an academicina and director of the Pulkovo observatory. He left this post in 1895 for reasons of health and settled in St. Peterburg, where he worked on his investigations of comets for the rest of his life.

Notwithstanding the great significance that Bredikhin ascribed to theoretical investigations, he was a tireless observer. His observations encompassed all major aspects of contemporary astronomy, including even gravimetry—which was then inextricably associated with astronomy. He observed comets with astronomical instruments and studied them, systematically drawing their heads and tails and the contours of solar protuberances and chromosphere; he also observed comets and gaseous nebulae with the aid of a spectroscope, as well as meteor showers and zodiacal light. In addition, he observed the surfaces of Jupiter (especially the famous red spot) and Mars and conducted gravimetric measurements at various locations in Russia.

Although the fundamental peculiarities of changes in the apparent shape of comets as they approach the sun had been noted before Bredikhin, he was the one who developed the so–called mechanical theory of a comet’s form. This theory’s basic premise, which dates as far back as Kepler and, ultimately, to Olbers, consists in the fact that particles of matter, which fly off from the core of the comet at a certain initial velocity, are repelled by the sun and, under the influence of that repulsion, move along hyperbolic trajectories. Bredikhin developed a method for determining the value of the repulsive accelerations (which are designated by 1 + μ) in the tails of comets and classified that tails according to these values: tails of type I are formed by forces of repulsion eleven to eighteen times greater than the sun’s gravity and are inclined directly away from the sun, although they bend slightly in the direction opposite to the motion of the comet; the tails of type II are wider and strongly bent, their repulsive accelerations encompassing all values from 0.7 to 2.2 times the force of the sun’s gravity; all tails of type III are even more inclined in the direction opposite that of the comet’s motion, with an acceleration from 0.1 to 0.3. The fourth (anomalous) type of tail, which is directed straight toward the sun, is seen very rarely and always with a tail of one of the first three types. Some comets have tails of two or three different types.

Bredikhin’s theory, which was based on an analysis of observations of about forty comets taken by himself and by others, explains several details of the structure of comets: the transverse bands in type II tails (synchrons), the motion of individual clumps in tails, and the form of a comet’s head. The physical ideas on which the ory of comet forms was based included the supposition of an interaction between the sun’s electric charge and the like charge of the gaseous molecules emanating from the comet’s core. The values of the repulsive accelerations of these molecules are inversely proportional to their molecular weights. From this, Bredikhin proposed that hydrogen molecules predominate in type I tails; that hydrocarbons and light metals, such as sodium, predominate in type II tails; and that type III tails might contain molecules of iron. Observations by Bredikhin and his contemporaries seemingly confirmed such an explanation. It has since been proved that type I tails containionized molecules of carbon monoxide and nitrogen, while tails of type II and type III consist of neutral gases and dust particles that reflect the rays of the sun.

Through the detailed study of spectra of the heads and tails of comets, the mechanical theory of comet forms has to a large degree been retained. The classification of comet tails proposed by Bredikhin and developed by S. V. Orlov has also retained its significance, Certain peculiarities of comets that follow Bredikhin’s theory, such as the parabolic shape of a comet’s head, rotation of the core, and the complex movements of clumps of matter in comets’ tails, have received exhaustive explanations in contemporary investigations. Bredikhin foresaw in the physical theory of comets the possibility of the influence if electrical forces, which also takes place in the interaction of solar corpuscular streams (so–called solar wind) and particles of matter in a comet.

He also devoted much attention to the study of meteor showers, which he believed occurred as the result of the earth’s intersection of a swarm of particles from the tails of comets, these particles having been gradually scattered along the comets’ orbits.

Bredikhin directed special attention to astrophysical investigations. In connection with his systematic observations of the sun, he developed a theory of the movement of matter in sunspots and in the rays of the solar corona. He proposed descending and ascending gaseous streams as the explanation of the formation of faculae and spots. On the basis of measurements made from photographs of eight total solar eclipses, taken between 1870 and 1896 by various astronomers, Bredikhin correctly noted the intimate connection between coronal eruptions and chromospheric protuberances and the absence of a direct connection between coronal eruptions and sunspots. Having determined that coronal eruptions are not radial, but somewhat curved, Bredikhin sought a similarity between them and the form of comet tails, proposing that a certain repulsive forces also acts on coronal eruptions. He also applied his mechanical theory of comet forms to the analysis of coronal rays. Only in recent times has the physics of the corona received solid substantiation inn the ory of the interaction between magnetic fields and a plasma, which is what the solar corona acutally is.

Bredikhin’s activity as director of the Pulkovo observatory greatly influenced the development of astronomy in Russia. Having replaced Struve, who strictly limited his contacts with other Russian university observatories and who preferred to have Germans and Swedes on the observatory staff, Bredikhin undertook a tour of all Russian observatories in order to familiarize himself with their activities, to help them obtain necessary instruments, to determine the most urgent scientific problems, and to attract the most talented young Russian astronomers to Pulkovo. In his first director’s report (for 1889–1891) he wrote: “To the alumni of all Russian universities… must be afforded, within the limits of possibility, free access [to the observatory]… the recruitment abroad of scientists for its staff must and can be stopped forever.” This greatly encouraged Russian astronomers, who now became frequent guests at Pulkovo, learned how to observe, and sometimes remained permanently. Before Bredikhin, there were only two Russians (A. A. Belopolsky and M. N. Morin) on the fifteen–man staff at Pulkovo; soon after he assumed the directorship, the number rose to nine.

Bredikhin was a charter member of the Mathematical Society in Moscow and an active member of the Moscow Society of Natural Scientists. In 1890 he was chairman of the Russian Astronomical Society, which had just been founded in St. Petersburg. He also belonged to many foreign organizations: the Astronomische Gesellschaft. Deutsche Aklademie der Naturforscher Leopoldina, the Royal Astronomical Society, the Italian Society of Spectroscopists, and the Bureau des Longitudes in Paris. In 1892 he was awarded an honorary doctorate by the University of Padua.

BIBLIOGRAPHY

I. Original Works. Bredikhin’s complete bibliography of published works contains over 200 titles. Among them are O khvostakh komet (“On the Tails of Comets”; Moscow, 1862; 2nd ed., K. D. Pokrovsky, ed., Moscow, 1934), 2nd ed. includes a biographical essay and a bibliography; “Protsess Galileya po novym dokumentam” (“The Trials of Galileo According of New Documents”), in Russkii vesinik, 92 , no. 4 (1871), 405–414; “O solnechnoy korone” (“On the Solar Corona”), in Izvestiya Imperatorskor akademii nauk, 5th ser., 9 no. 3 (1898), 179–207; Prof. Th. Bredikhin’s mechanische Untersuchungen über Cometenformen in systematischer Darstellung, R. Jaegermann, compil. (Leipzig, 1903), a systematic survey of all of Bredikhin’s papers on the mechanical theory of comet forms, compiled under his supervision; Études sur l’origine des météores cosmiques et la formation de leurs courants (St. Petersburg, 1903), Bredikhin’s survey monograph on meteor showers; and Etyudy o meteorakh (“Studies on Meteors”), S. V. Orlov, ed. (Moscow, 1954), with an article and commentart by A. D. Dubyago. His correspondence is in the archives, Academy of Sciences, Leningrad.

II. Secondary Literature. Works on Bredikhin include A. A. Belopolsky, “Fedor Aleksandrovich Bredikhin”, in Izvestiya Imperatorskoi akademii nauk, 5th ser., 21 no. 2 (1904), i–iv, and “Fizicheskoe stroenie kometnykh khvostov” (“The Physical Structure of Comet Tails”), in Russkii astronomicheskii kalendar na 1927 god (“Russian Astronomical Calender for 1927”; Nizhni Novgorod, 1926), pp. 137–161; S. K. Kostinsky, “Fedor Aleksandrovich Bredikhin”, in Russkii astronomicheskii kalendar no 1905 god (“Russian Astronomical Calender for 1905”; Nizhni Novgorod, 1904), pp. 2–29; B. Y. Levin, “F. A. Bredikhin”, in Lyudi russkoy nauki (“People of Russian Science”; Moscow, 1961), pp. 141–151; O. A. Melnikov, “Fedor Aleksandrovich Bredikhin (k 125–letiyu so duya rozhdenia)” (“Fedor Aleksandrovich Bredikhin: On the 125th Anniversary of the Day of His Birth”), in Izvestiya GAO v Pulkove, 20 , pt. 6, no. 159 (1958), 1–27; N. I. Nevskaya, Fedor Aleksandrovich Bredikhin (1831–1904) (Moscow–Leningrad, 1964), the most complete biography, with a bibliography of all his works and of 252 secondary sources; S. V. Orlov, Fedor Aleksandrovich Bredikhin (1831–1904) (Moscow, 1948), a biographical essay with a bibliography of both original and secondary works; and K. D. Pokrovsky, “Teoria kometnykh form” (“the ory of Comet Forms”), in Russkii astromomicheskii kalendar na 1905 god (“Russian Astronomical Calendar for 1905”, Nizhni Novgorod, 1904), pp. 35–51.

P.G. Kulikovsky