Carl Jensen Burrau

Background

Carl Jensen Burrau was born on July 29, 1867, in Elsinore, Denmark.

Education

Burrau studied mathematics at Copenhagen University.

Career

While studying at Copenhagen University, Burrau was also an assistant astronomer at the university observatory from 1893 to 1898. He subsequently worked as an actuary. From 1906 to 1912 he lectured at Copenhagen University on practical mathematics. In his researches as an astronomer and as an actuary he was a disciple of T. N. Thiele.

In 1892 the Royal Danish Academy, at Thiele’s suggestion, presented an astronomical prize problem concerning librations in the problème restreint with two equal masses in circular movement round their common center of gravity. In his solution, Burrau was the first to point out that a series of periodic orbits, into which the third (massless) body moves, develops into a limiting orbit of ejection from (or collision with) one of the masses.

Burrau’s dissertation (1895) deals with the derivation of the constants of a measuring machine for photographic determination of star positions. He suggested the development of Bessel’s classic method and discussed previously proposed simplifications. The “distance” from these studies to actuarial work is short.

Burrau’s little book on actuarial mathematics, Forsikringsstatistikens Grundlag, which was originally written as a series of lectures and appeared in Danish, German, and Italian, is a similar attempt to use his mathematical knowledge in the domain in which he worked for most of his life. Later, he and B. Stromgren published a paper on dividing a frequency curve into its components.

Achievements

• Carl Burrau's pioneer achievement was in his solution, where he became the first to point out that a series of periodic orbits, into which the third (massless) body moves, develops into a limiting orbit of ejection from (or collision with) one of the masses. It was the first step taken in the systematic search for periodic orbits in the three-body problem.

Works

More photos

• book

  • Tafeln Der Funktionen Cosinus Und Sinus: Mit Den Natürlichen Sowohl Reellen ALS Rein Imaginären Zahlen ALS Argument: Kreis Und Hyperbelfunctionen 1907

Personality

Quotes from others about the person

• In an obituary, Kristensen, who audited Burrau’s lectures on practical mathematics, mentions “his ability to combine scientific points of view with instructions for using them in practice."

Connections

collaborator:

Bengt Georg Daniel Strömgren

Strömgren made momentous contributions to astrophysics. He found that the chemical composition of stars was very much different than previously assumed. In the late 1930s, he found the relative abundance of hydrogen to be nearly 70%, and helium to be about 27%. Just before the war, he discovered the so-called Strömgren Spheres — huge interstellar shells of ionized hydrogen around stars. And in the 1950s and 1960s, he pioneered photoelectric photometry with a novel four-color system, now called Strömgren photometric system.

colleague:

Nicholas Nicolai Thiele

References

• Dictionary of scientific biography
  1981