|Photo courtesy Prof. Adriaan Blaauw, Univ. of Leiden|
|8 October 1873||1937 Bruce Medalist||21 October 1967|
Ejnar Hertzsprung studied chemical engineering in Copenhagen, worked as a chemist in St. Petersburg, and studied photochemistry in Leipzig before returning to Denmark in 1901 to become an independent astronomer. In 1909 he was invited to Göttingen to work with Karl Schwarzschild, whom he accompanied to the Potsdam Astrophysical Observatory later that year. From 1919 - 44 he worked at the Leiden Observatory in the Netherlands, the last nine years as director. He then retired to Denmark but continued measuring plates into his nineties. He is best known for his discovery that the variations in the widths of stellar lines discovered by Antonia Maury reveal that some stars (giants) are of much lower density than others (main sequence or “dwarfs”) and for publishing the first color-magnitude diagrams. He was the first to calibrate the period-luminosity relation for Cepheid variable stars and he used it to estimate the distance to the Small Magellanic Cloud. He also determined proper motions, colors, and magnitudes of thousands of stars in the Pleiades cluster, and he measured about a million photographic positions of binary stars.
Presentation of Bruce medal
Leuschner, A.O., PASP 49, 65-81 (1937).
Royal Astronomical Society, Gold medal, 1929, presented by T.E.R. Phillips, MNRAS 89, 404-17 (1929).
Andrews, A.D., “Ejnar Hertzsprung’s 90th Birthday,” Irish Astronomical Journal 6, 150-51 (1963).
Beckett, Elizabeth, Holly Bernitt, and Vishwa Chandra, “Ejnar Hertzsprung”
Herrmann, Dieter B., Ejnar Hertzsprung - Pionier der Sternforschung (Springer-Verlag, Berlin, NY, 1994). A shorter version appeared in Sterne 72, 1, 60-61 (1996).
Herrmann, Dieter B., Biographical Encyclopedia of Astronomers (Springer, NY, 2007), pp. 496-97.
Poulsen, Erling Rundetaarn Observatory
Strand, K. Aa., Dictionary of Scientific Biography 6, 350-53.
Urania Observatory, Denmark [in Danish].
van Helden, Albert, in K.v. Berkel, A.v. Helden, & L. Palm, eds., A History of Science in The Netherlands (Brill, Leiden, 1999), pp. 460-63.
Hellyer, B., Journ. British Astron. Ass. 83, 460-461 (1973).
Strand, K. Aa. PASP 80, 51-56 (1968).
Wesselink, A., QJRAS 9, 337-41 (1968).
Nielsen, Axel V., Sky & Telescope 35, 4-6 (1968).
Oosterhoff, P.Th., Astron. Nachr. 291, 85-87 (1969) [This is a German translation from Dutch].
AIP Center for History of Physics
Astronomes Amateurs du Luxembourg
Les Amis du Planétarium de Reims
Urania Observatory, Denmark
Named after him
Lunar crater Hertzsprung
Minor Planet #1693 Hertzsprung
The Hertzsprung-Russell Diagram (with H.N. Russell)
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