STRöMGREN, SVANTE ELIS

(b. Hälsingborg, Sweden, 31 May 1870; d. Copenhagen, Denmark, 5 April 1947)

astronomy.

Strömgren studied astronomy at the University of Lund, where he received his doctorate in 1898. He spent the years 1901–1907 at Kiel, as assistant to the editor of Astronomische Nachrichten, and beginning in 1904 he was a lecturer at Kiel University. From 1907 to 1940 he was professor of astronomy at Copenhagen University and director of the observatory. Strömgren’s research belongs to the tradition of classical celestial mechanics, even though he used elaborate mathematical apparatus to make numerical computations more than most members of this school did.

In his dissertation Strömgren derived the definitive orbit of Comet 1890 II, which, like most comets, followed an approximately parabolic path relative to the sun. This investigation was the first of a series of papers on the original orbits of such comets–open or closed–and was crucial for work on the cosmogony of comets. In“Ueber den Ursprung der Kometen”(1914), Strömgren concluded that all comets of which the orbits had been determined with sufficient accuracy for a decision about their return to be possible, have followed closed orbits; the hyperbolic motion derived for several comets was a consequence of the perturbations of the large planets during their passage through the internal regions of the solar system. About thirty years later his investigations formed the starting point for J. H. Oort’s and A. J. J. van Woerkom’s“discovery”of the comet cloud far outside the planetary orbits.

Strömgren’s survey of the three-body problem was concerned with two equal masses moving in circular orbits around a common center of gravity and with a body without mass–a problème restreint. The movement of the third body was derived by numerical integration with the aim of determining the orbits, which are periodic relative to the coordinate system, in which the main bodies are relatively at rest. With J. Fischer-Petersen and J. P. Møller, Strömgren pointed out a number of groups of simple-periodic orbits. Strömgren’s pioneer work has recently been the starting point for further surveys because electronic computers have greatly simplified the routine computational work. In“Connaissance actuelle des orbites dans le problème des trois Corps”(1935), Strömgren gave a general view of the work done at Copenhagen.

Strömgren held a major position in international astronomical collaboration. From 1922 to 1947 he was director of the telegram bureau for astronomical news sponsored by the International Astronomical Union; and as early as 1914, at the outbreak of World War I, Strömgren had established a“neutral bureau”at the Copenhagen observatory, as a branch of the old Kiel bureau. During World War II he maintained the news service at the Lund observatory as a neutral branch bureau. From 1921 to 1930 he was president of the Astronomische Gesellschaft.

Strömgren’s textbook of astronomy for students at Copenhagen University was translated into German and enlarged by Bengt Strömgren in 1933. Unique for its time, the work deals with both classical and modern stellar astronomy and astrophysics. From 1920 to 1947 Strömgren was president of the Astronomisk Selskab (Copenhagen) and was editor-in-chief of Nordisk astronomisk tidsskrift. He also took a strong interest in the Variable Star Section sponsored by the Astronomisk Selskab. A distinguished Latin scholar, Strömgren had a major role in the translation into modern languages of Tycho Brahe’s book on his own instruments and of Peder Horrebow’s description of Ole Römer’s instruments.

BIBLIOGRAPHY

Original Works. A bibliography of Strömgren’s papers and books (1896–1940) was edited by K. Lundmark in Astronomical Papers, Dedicated to Elis Strömgren (Copenhagen, 1940). His principal works are“Ueber den Ursprung der Kometen,”in Kongelige Danske Videnskabernes Selskahs Skrifter, 7th ser., Naturv.-mathem. Afd., 11 , p. 4 (1914), 189–251;“Connaissance actuelle des orbites dans le problème des trois corps,”in Bulletin astronomique, 2nd ser., 9 (1935), 87–130; and Ole Rømer som Astronom (Copenhagen. 1944).

With Bengt Strömgren he was coauthor of Lehrbuch der Astronomie (Berlin, 1933); and with Bengt Strömgren and Hans Raeder, Tycho Brahe’s Description of His Instruments and Scientific Work . . . (Copenhagen, 1946).

See also Publikationer og mindre Meddelelser fra Kjøbenhavns Observatorium (1910–1947) and“Tre Aartier celest Mekanik paa Kjøbenhavns Observatorium,” in Festskrift, Copenhagen University (Nov. 1923).

II. Secondary Literature. Obituaries are J. M. V. Hansen, in Nordisk astronomisk tidsskrift (1947), 41–43; in Observatory, 67 (1947), 142–143; and in Popular Astronomy, 55 (1947), 341–343; B. Lindblad, in Nordisk astronomisk tidsskrift (1947), 43;and in Populär astronomisk tidsskrift, 28 (1947), 59–60; K. Lundmark, in Monthly Notices of the Royal Astronomical Society, 108 (1948), 37–41; and N. E. Nørlund, in Festskrift, Copenhagen University (Nov. 1947), 149–152; and in Oversigt over det K. Danske Videnskabernes Selskabs Forhandlinger (1948), 73–77. See also R. Grammel,“E. Strömgrens Arbeiten zum Dreikörperproblem,” in Viertejahrsschrift der Astronomischen Gesellschaft, 64 (1929), 90–100.

Axel V. Nielsen