Quarter 3 Biography

Ejnar Hertzsprung is a very famous astronomer who is often compared to Tycho Brahe and Copernicus despite the fact that he was never really a professional astronomer. Born in 1873, Hertzsprung grew up in Copenhagen, Denmark and lived with a father, Severin Hertzsprung, that was obsessed with astronomy despite his lack of ability to get a career in the field. Ejnar was always obsessed with his fathers’ charts and maps. In college, Ejnar studied chemistry and had a job for three years in St. Petersburg in the field at the Wilhelm Ostwald Laboratory but he also volunteered his spare time at the Urania Observatory. In 1902, his brother died and he decided to move back to his home town where he became a private scientist, a rather unsuccessful one at that. Then he made a breakthrough in 1905 when he published "Zur Strahlung der Sterne" in "Zeitschrift für Wissenschaftliche Photographie". In this publication, he said, “Stars in the late spectral-classes (G, K and M) are divided into two series with different luminosity. The luminous red stars must be very big. The little number of red giants (he does not use that term) shows that these stars are in a stage of fast evolution.” This basically means that he realized for the first time in history that there is a correlation between the spectrum and luminosity. In 1907, he published another astronomy document called, "Zur Bestimmung der photographischen Sterngrössen". In this he has photographs and questions about stars. As a result of this, he met with Schwarchild in 1908 and they moved in together in 1910 to the US. He and a man he met in the US named Henry Russell worked together and published the first version of the Hertzsprung – Russell Diagram in the year 1911. For the Hyades above and the Pleiades below, the ordinate shows the effective wavelength of the light in Angstrom, the abscissa shows (from above) the visual magnitude, absolute magnitude and visual magnitude. This quote is from their publication "Publikationen des Astrophysikalischen Observatorium zu Potsdam". In 1913, he actually was able to calculate the distance to the small Magellan Cloud, this was the first distance to an object outside the Milky Way to be calculated properly and he used the delta cephei type of variable stars. During this time in the USA, Ejnar met and married his wife Henrietta Hertzsprung-Kapteyn who he stayed with for the rest of his life. After all of these discoveries, Ejnar got a job at the Leiden University Observatory for twenty six years between 1919 and 1945 and even became the lead director there in 1935. With further observations of stars, he made even more discoveries in the evolution of the open star clusters and variable stars. Hertzsprung also developed a vastly improved method to determine the relative positions of the components of double stars Hertzsprung remained an active researcher until he was over 90 years old. He was actually the very last self-taught astronomers to oversee this major observatory that is still in use to this day. He died in 1967 in Roskilde, Denmark, and his papers (12,153 pages with original measurements) were given to the U. S. Naval Observatory Library where his former student, Strand, was the director. Throughout his life, Ejnar Hertzsprung won dozens of awards and recognitions but some of the most prominent incoude the Bruce Medal in 1937, the Royal Astronomical Society Gold Medal and the Royal Astronomical Society silver medal in 1929, the Asteroid Namesake award where an asteroid was named 1693 Hertzsprung, and had a Lunar Crater named after him (the Hertzsprung Crater). Ejnar Hertzsprung was an amazing astronomer who accomplished more for astronomy than most people can even dream.