Bengt Strömgren: Growing up with Astronomy,1908–1932

Bengt Strömgren , “Astronomy made easy” (unpublished manuscript written c. 1955, BSA, manuscripts).

Bibliographic database of NASA Astrophysics Data System on the Internet, http://adswww.harvard.edu. A selected biography is given in Nissen Erik Poul Bengt Gustafsson , “Astrophysics: Recent progress and future possibilities. Invited reviews at a symposium in honour of Bengt Strömgren (1908–1987)”, The Royal Danish Academy of Sciences and Letters , iii (1990), 9–12.

Née Lidforss , 1877–1967. Besides being a dentist, Hedvig Strömgren was a productive writer on the history of odontology in Scandinavia as well as in ancient Rome.

Bengt was named after his maternal uncle, the botanist Bengt Lidforss, “Georg” after a paternal ancestor, and “Daniel” on account of this name's beauty. Karl Hufbauer, unpublished notes shared with the author (1999), based on interviews with Ole Strömgren (son of B. Strömgren) on 16 November 1998, and others, 7 January 1999.

Hjalmar Havelund , Berlingske Tidende , 15 January 1978, 12–13.

HBI, 2.

The group consisted of Strömgren E. Hansen Julie M. V. (a newly employed observer, from 1930 editor of N.A.T.), Aage Nielsen Møller Jens P. , see Bengt Strömgren , “Komet 1922c (Baade)”, Astronomische Nachrichten , ccxvii (1922), cols 345–8.

Strömgren , op. cit. (ref. 7).

According to Nissen Gustafsson , op. cit. (ref. 2), 7, Bengt's first publication appeared when he was 17 years old. This is evidently not correct. Even though the joint paper on Comet Baade from 1922 was a mere table of data rather than an actual full article, it was indeed a publication.

Bengt Strömgren , “Bestimmung der Rektascenzionen von 131 polnahen Sternen: Nach Beobachtungen von Bengt Strömgren und J. Johannsen in den Jahren 1921–1923 angestellt am Repsoldschen Durchgangsinstrument der Kopenhagener Sternwarte”, Kunglige Svenska Vetenskapsakademiens Handlinger , ser 2, iii, no. 2 (1925).

BSA, uncatalogued (20 and 21 May 1967, Bengt Strömgren's own handwriting in Danish).

He graduated on 4 June 1925 and won the Andræ'ske Rejselegat, see Indbydelsesskrift til den offentlige Examen i Metropolitanskolen [Copenhagen], May-June 1926, 4, 33.

The General Assembly in Cambridge, 14–22 July 1925, was the second international meeting of this kind (the first having been in Rome, 2–10 May 1922). 189 astronomers attended this assembly, and at its conclusion the union counted 22 member states, see Adriaan Blaauw , History of the IAU: The birth and first half-century of the International Astronomical Union (Dordrecht, 1994), 81.

Blaauw , op. cit. (ref. 13), 76.

Blaauw , op. cit. (ref. 13), 77.

Janssen Emil Luplau Carl , “Astronomisk Tidsskrift”, Nordisk Astronomisk Tidsskrift , 1916, 1. The Danish name Astronomisk Selskab means Astronomical Society.

Gustav Holmberg , Reaching for the stars: Studies in the history of Swedish stellar and nebular astronomy 1860–1940 (Lund, 1999), 132.

On the history of UITF, see Peter Robertson , The early years: The Niels Bohr Institute 1921–1930 (Copenhagen, 1979), and Finn Aaserud , Redirecting science (New York, 1990).

Strömgren B. was appointed on a one-year basis from 1 November 1926. His Assistantship was extended a year at a time until 1932 when he was appointed lecturer in astronomy, see Yearbook 1926–1927, Årbog for Københavns Universitet, Den Polytekniske Læreanstalt og Kommunitetet , 13.

In a letter from UITF to Strömgren B. , he was thanked for his excellent calculation work, and sent 125 Danish Crowns (NBA, Bengt Strömgren, 23 November 1923).

Bengt Strömgren , “Scientists I have known and some astronomical problems I have met”, Annual review of astronomy and astrophysics , xxi (1983), 1–11, p. 2.

HBI, 11.

Kramers went to Copenhagen after a visit to Leiden in 1916, and after the inauguration of UITF in 1921, he served as first assistant followed by a lectureship in the period 1924–26; Oskar Klein worked at UITF in two spells, the first being from 1918 to 1922, the second from 1926 to 1931, Robertson , op. cit. (ref. 18).

Robertson , op. cit. (ref. 18), 111.

Strömgren , op. cit. (ref. 21), 2.

HBI, 10. It should be noted that this obviously is a retrospective recollection on the part of Strömgren, which therefore may be coloured by knowledge about what happened afterwards. Nevertheless, the reminiscence is Strömgren's own. Klein published his most important papers in the German physics journal Zeitschrift für Physik , and his only paper published there in 1927 was Oskar Klein , “Elektrodynamik und Wellenmechanik vom Standpunkt des Korrespondenzprinzips”, Zeitschrift für Physik , xli (1927), 407–42. This therefore is presumably the paper referred to by Strömgren.

Strömgren , op. cit. (ref. 21), 2.

Op. cit. (ref. 11).

HBI, 11. Werner Heisenberg , “Über den anschaulichen Inhalt der quantentheoretischen Kinematik und Mechanik”, Zeitschrift für Physik , xliii (1927), 172–98.

Strömgren , op. cit. (ref. 21), 3.

HBI, 11.

HI, 4.

HBI, 12.

BSA, miscellaneous, “Om Solens och Stjärnornas Utveckling (foreløbigt program)”, a talk given at the 18^th Scandinavian Natural Science Researchers' meeting, 27 August 1929.

Bengt Strömgren , “Formeln zur genäherten Störungsrechnung in Bahnelementen”, Royal Danish Academy of Sciences and Letters , lxv (1929), 1–26, and “Formeln und Tafeln zur Bestimmung parabolischen Bahnen”, ibid. , lxvi (1929), 1–150 (doctoral thesis).

Correspondence between the author and Bengt's two daughters, Allen Strömgren Nina Strömgren Campbell Karin , 2002.

Eddington Stanley Arthur , The internal constitution of the stars (Cambridge, 1926). Regarding the “instant classic” designation, see Karl Hufbauer , “Stellar structure and evolution [1924–1938]”, unpublished draft chapter for The general history of astronomy , written May 1990, 1–29, p. 8.

Cecilia Payne-Gaposchkin , Cecilia Payne-Gaposchkin: An autobiography and other recollections , ed. by Katherine Haramundanis (Cambridge, 1996), 25.

Robert Emden , Gaskugeln: Anwendungen der Mechanischen Warmetheorie (Leipzig, 1907).

The constant a is the so-called radiation constant: a = 4σ/c (where σ is the Stefan-Boltzmann constant, c the constant speed of light).

Here>, M is the mass (as function of r), the radiation pressure is p_r, κ the opacity, ε the energy generation per unit mass, and μ is the mean molecular weight.

The stellar luminosity L is defined as the total radiation flux emitted in space from the star in all directions, per unit time, and is given by L = 4πr²F for an ideal spherical star with radius r, which emits its radiation isotropically with the total flux F..

Eddington , op. cit. (ref. 37), 146. G is the constant of gravitation.

An amount of matter is said to be in radiative equilibrium when there is a constant net-flux of radiation through the matter, e.g. through an atmospheric layer, and when all energy is transported by means of radiation only. Furthermore, inward gravitational pressure is counterbalanced by the outward pressure of radiation.

Eddington , op. cit. (ref. 37), 14.

With given values of visual magnitude, spectral type (yielding knowledge about effective temperatures) and mass, the latter calculated mechanically by use of Kepler's third law based on observed orbital motion giving empirical values of semiaxes, orbital period and mass-ratios.

Bengt Strömgren , “The rise of astrophysics”, Annals of the New York Academy of Science , cxcviii (1972), 245–54, p. 246.

They found effective pressures in the Sun's and other stellar photospheres around P_e = 10⁻⁴ atm. for most of the elements, see David DeVorkin , “Quantum physics and the stars (I): The establishment of a stellar temperature scale”, Journal for the history of astronomy , xiv (1983), 102–32.

DeVorkin , op. cit. (ref. 48), 122.

David DeVorkin , Henry Norris Russell: Dean of American astronomers (Princeton, 2000).

Russell Norris Henry , “On the composition of the Sun's atmosphere”, Astrophysical journal , lxx (1929), 11–82.

See e.g. Helge Kragh Simon Rebsdorf , “Before cosmophysics: E. A. Milne on mathematics and physics”, Studies in history and philosophy of modem science , xxxiii (2002), 35–50.

Greaves W. M. H. (ed.), “Meeting of the Royal Astronomical Society”, The observatory , liv (1931), 33–45, p. 36.

Cowling Thomas G. , “The development of the theory of stellar structure”, Quarterly journal of the Royal Astronomical Society , vii (1966), 121–37, p. 126.

Bengt Strömgren , “The point source model with coefficient of opacity k = k₁ρT^−3.5”, Zeitschrift für Astrophysik , ii/5 (1931), 345–69, p. 369.

Kragh Rebsdorf , op. cit. (ref. 52), 39. See also Simon Rebsdorf Helge Kragh , “Edward Arthur Milne: The relations of mathematics to science”, Studies in history and philosophy of modern science , xxxiii (2002), 51–64, p. 52.

Strömgren , op. cit. (ref. 55), 369.

Ibid. .

BSA, A08, 16 February 1931, Strömgren B. Milne E. A. .

Cowling Thomas G. , “Astronomer by accident”, Annual review of astronomy and astrophysics , xxiii (1985), 1–18.

Strömgren , op. cit. (ref. 21), 3.

Kramers Anton Hendrik , “On the theory of X-ray absorption and of the continuous X-ray spectrum”, Philosophical magazine , xlvi (1923), 836–71.

Gaunt John A. , “Continuous absorption”, Philosophical transactions of the Royal Society , ccxxix (1930), 163–204. Gaunt refers to Oppenheimer Robert J. , “Zur Quantentheorie kontinuierlicher Sprektren”, Zeitschrift für Physik , xli (1927), 268–93.

Gaunt , op. cit. (ref. 63), 204.

Elis Strömgren held the position of professor of astronomy at the Copenhagen Observatory from 1907 until he was succeeded by his son on his retirement in 1940.

HBI, 18.

HBI, 18.

HBI, 18.

Comrie John Leslie (1893–1950) from New Zealand was an astronomer and pioneer in mechanical computation, working in England for many years. ESC, 8 August 1931, Strömgren E. (London) to Strömgren B. (Copenhagen).

Yoshikatse Sugiura , “The angular intensity distribution of continuos X-ray spectrum IV: Some notes on the stellar opacity coefficient”, Scientific papers of the Institute of Physical and Chemical Research (Tokyo), cccxxxix (1931), 89–110. Sugiura visited the UITF in the period 1925–27, Robertson , op. cit. (ref. 18), 158.

Bengt Strömgren , “The opacity of stellar matter and the hydrogen content of stars”, Zeitschift für Astrophysik , iv (1932), 118–53, p. 120.

Biermann received his doctoral degree in Göttingen with a dissertation on convection in stellar interiors.

Strömgren , op. cit. (ref. 71), 121.

Strömgren , op. cit. (ref. 71), 119.

Strömgren , op. cit. (ref. 71), 150–1.

Strömgren , op. cit. (ref. 71), 151.

HBI, 45.

Strömgren , op. cit. (ref. 21), 3.

Eddington , op. cit. (ref. 37), 249.

DeVorkin , op. cit. (ref. 50), 247.

Strömgren , op. cit. (ref. 71), 122.

Mitra Nath Shailendra , “A note on the abundance of hydrogen in the white dwarfs”, Zeitschift für Astrophysik , iv (1932), 329–30.

Mitra , op. cit. (ref. 82), 330. Within the sociology of science, such synchronous scientific enterprises are known as multiplets, meaning discoveries made simultaneous and independently by different scientists or science teams. See e.g. Helge Kragh , An introduction to the historiography of science (Cambridge, 1987).

Eddington A. S. , “The hydrogen content of the stars”, Monthly notices of the Royal Astronomical Society , xcii (1932), 471–81, p. 473.

BSA, A03, 17 March 1932, Eddington A. S. Strömgren B. . Krueger 60 is a double star system, which was frequently used in examples of astrophysical calculations: Eddington , op. cit. (ref. 37), 150.

Eddington , op. cit. (ref. 84), 473.

Eddington A. S. , “The ‘guillotine factor’ in stellar opacity”, Monthly notices of the Royal Astronomical Society , xcii (1932), 364–9.

Eddington , op. cit. (ref. 87), 364.

BSA, A03, 2 April 1932, Strömgren B. to A.S. Eddington.

Strömgren , op. cit. (ref. 47), 246.

Ibid. .

Strömgren , op. cit. (ref. 21), 3.

Bengt Strömgren , “On the interpretation of the Hertzsprung-Russell-Diagram”, Zeitschift für Astrophysik , vii (1933), 222–48.

BSA, A02, 26 May 1933, Chandrasekhar S. to Strömgren B. .

BSA, A02, 11 June 1933, Chandrasekhar S. Strömgren B. .

Ibid. .

Ibid.; R-M refers to radius-mass.

Sitterly Bancroft W. , Vistas in astronomy , xii (1970), 357–66, p. 363.